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![Igor Stoppa](/assets/img/avatar_default.png)
WARN_ON() already contains an unlikely(), so it's not necessary to wrap it into another. Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1942 lines
44 KiB
C
1942 lines
44 KiB
C
/*
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* Copyright (C) 2015 Red Hat. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#include "dm-cache-background-tracker.h"
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#include "dm-cache-policy-internal.h"
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#include "dm-cache-policy.h"
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#include "dm.h"
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#include <linux/hash.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/vmalloc.h>
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#include <linux/math64.h>
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#define DM_MSG_PREFIX "cache-policy-smq"
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/*----------------------------------------------------------------*/
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/*
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* Safe division functions that return zero on divide by zero.
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*/
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static unsigned safe_div(unsigned n, unsigned d)
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{
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return d ? n / d : 0u;
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}
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static unsigned safe_mod(unsigned n, unsigned d)
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{
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return d ? n % d : 0u;
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}
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/*----------------------------------------------------------------*/
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struct entry {
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unsigned hash_next:28;
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unsigned prev:28;
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unsigned next:28;
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unsigned level:6;
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bool dirty:1;
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bool allocated:1;
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bool sentinel:1;
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bool pending_work:1;
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dm_oblock_t oblock;
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};
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/*----------------------------------------------------------------*/
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#define INDEXER_NULL ((1u << 28u) - 1u)
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/*
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* An entry_space manages a set of entries that we use for the queues.
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* The clean and dirty queues share entries, so this object is separate
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* from the queue itself.
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*/
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struct entry_space {
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struct entry *begin;
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struct entry *end;
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};
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static int space_init(struct entry_space *es, unsigned nr_entries)
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{
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if (!nr_entries) {
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es->begin = es->end = NULL;
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return 0;
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}
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es->begin = vzalloc(array_size(nr_entries, sizeof(struct entry)));
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if (!es->begin)
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return -ENOMEM;
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es->end = es->begin + nr_entries;
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return 0;
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}
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static void space_exit(struct entry_space *es)
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{
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vfree(es->begin);
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}
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static struct entry *__get_entry(struct entry_space *es, unsigned block)
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{
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struct entry *e;
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e = es->begin + block;
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BUG_ON(e >= es->end);
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return e;
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}
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static unsigned to_index(struct entry_space *es, struct entry *e)
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{
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BUG_ON(e < es->begin || e >= es->end);
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return e - es->begin;
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}
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static struct entry *to_entry(struct entry_space *es, unsigned block)
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{
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if (block == INDEXER_NULL)
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return NULL;
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return __get_entry(es, block);
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}
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/*----------------------------------------------------------------*/
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struct ilist {
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unsigned nr_elts; /* excluding sentinel entries */
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unsigned head, tail;
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};
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static void l_init(struct ilist *l)
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{
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l->nr_elts = 0;
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l->head = l->tail = INDEXER_NULL;
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}
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static struct entry *l_head(struct entry_space *es, struct ilist *l)
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{
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return to_entry(es, l->head);
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}
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static struct entry *l_tail(struct entry_space *es, struct ilist *l)
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{
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return to_entry(es, l->tail);
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}
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static struct entry *l_next(struct entry_space *es, struct entry *e)
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{
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return to_entry(es, e->next);
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}
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static struct entry *l_prev(struct entry_space *es, struct entry *e)
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{
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return to_entry(es, e->prev);
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}
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static bool l_empty(struct ilist *l)
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{
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return l->head == INDEXER_NULL;
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}
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static void l_add_head(struct entry_space *es, struct ilist *l, struct entry *e)
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{
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struct entry *head = l_head(es, l);
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e->next = l->head;
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e->prev = INDEXER_NULL;
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if (head)
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head->prev = l->head = to_index(es, e);
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else
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l->head = l->tail = to_index(es, e);
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if (!e->sentinel)
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l->nr_elts++;
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}
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static void l_add_tail(struct entry_space *es, struct ilist *l, struct entry *e)
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{
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struct entry *tail = l_tail(es, l);
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e->next = INDEXER_NULL;
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e->prev = l->tail;
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if (tail)
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tail->next = l->tail = to_index(es, e);
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else
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l->head = l->tail = to_index(es, e);
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if (!e->sentinel)
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l->nr_elts++;
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}
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static void l_add_before(struct entry_space *es, struct ilist *l,
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struct entry *old, struct entry *e)
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{
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struct entry *prev = l_prev(es, old);
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if (!prev)
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l_add_head(es, l, e);
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else {
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e->prev = old->prev;
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e->next = to_index(es, old);
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prev->next = old->prev = to_index(es, e);
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if (!e->sentinel)
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l->nr_elts++;
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}
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}
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static void l_del(struct entry_space *es, struct ilist *l, struct entry *e)
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{
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struct entry *prev = l_prev(es, e);
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struct entry *next = l_next(es, e);
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if (prev)
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prev->next = e->next;
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else
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l->head = e->next;
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if (next)
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next->prev = e->prev;
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else
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l->tail = e->prev;
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if (!e->sentinel)
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l->nr_elts--;
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}
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static struct entry *l_pop_head(struct entry_space *es, struct ilist *l)
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{
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struct entry *e;
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for (e = l_head(es, l); e; e = l_next(es, e))
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if (!e->sentinel) {
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l_del(es, l, e);
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return e;
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}
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return NULL;
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}
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static struct entry *l_pop_tail(struct entry_space *es, struct ilist *l)
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{
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struct entry *e;
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for (e = l_tail(es, l); e; e = l_prev(es, e))
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if (!e->sentinel) {
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l_del(es, l, e);
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return e;
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}
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return NULL;
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}
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/*----------------------------------------------------------------*/
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/*
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* The stochastic-multi-queue is a set of lru lists stacked into levels.
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* Entries are moved up levels when they are used, which loosely orders the
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* most accessed entries in the top levels and least in the bottom. This
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* structure is *much* better than a single lru list.
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*/
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#define MAX_LEVELS 64u
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struct queue {
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struct entry_space *es;
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unsigned nr_elts;
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unsigned nr_levels;
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struct ilist qs[MAX_LEVELS];
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/*
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* We maintain a count of the number of entries we would like in each
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* level.
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*/
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unsigned last_target_nr_elts;
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unsigned nr_top_levels;
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unsigned nr_in_top_levels;
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unsigned target_count[MAX_LEVELS];
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};
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static void q_init(struct queue *q, struct entry_space *es, unsigned nr_levels)
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{
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unsigned i;
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q->es = es;
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q->nr_elts = 0;
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q->nr_levels = nr_levels;
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for (i = 0; i < q->nr_levels; i++) {
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l_init(q->qs + i);
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q->target_count[i] = 0u;
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}
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q->last_target_nr_elts = 0u;
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q->nr_top_levels = 0u;
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q->nr_in_top_levels = 0u;
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}
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static unsigned q_size(struct queue *q)
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{
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return q->nr_elts;
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}
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/*
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* Insert an entry to the back of the given level.
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*/
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static void q_push(struct queue *q, struct entry *e)
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{
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BUG_ON(e->pending_work);
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if (!e->sentinel)
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q->nr_elts++;
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l_add_tail(q->es, q->qs + e->level, e);
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}
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static void q_push_front(struct queue *q, struct entry *e)
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{
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BUG_ON(e->pending_work);
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if (!e->sentinel)
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q->nr_elts++;
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l_add_head(q->es, q->qs + e->level, e);
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}
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static void q_push_before(struct queue *q, struct entry *old, struct entry *e)
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{
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BUG_ON(e->pending_work);
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if (!e->sentinel)
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q->nr_elts++;
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l_add_before(q->es, q->qs + e->level, old, e);
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}
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static void q_del(struct queue *q, struct entry *e)
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{
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l_del(q->es, q->qs + e->level, e);
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if (!e->sentinel)
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q->nr_elts--;
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}
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/*
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* Return the oldest entry of the lowest populated level.
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*/
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static struct entry *q_peek(struct queue *q, unsigned max_level, bool can_cross_sentinel)
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{
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unsigned level;
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struct entry *e;
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max_level = min(max_level, q->nr_levels);
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for (level = 0; level < max_level; level++)
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for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e)) {
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if (e->sentinel) {
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if (can_cross_sentinel)
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continue;
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else
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break;
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}
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return e;
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}
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return NULL;
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}
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static struct entry *q_pop(struct queue *q)
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{
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struct entry *e = q_peek(q, q->nr_levels, true);
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if (e)
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q_del(q, e);
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return e;
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}
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/*
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* This function assumes there is a non-sentinel entry to pop. It's only
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* used by redistribute, so we know this is true. It also doesn't adjust
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* the q->nr_elts count.
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*/
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static struct entry *__redist_pop_from(struct queue *q, unsigned level)
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{
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struct entry *e;
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for (; level < q->nr_levels; level++)
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for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e))
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if (!e->sentinel) {
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l_del(q->es, q->qs + e->level, e);
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return e;
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}
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return NULL;
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}
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static void q_set_targets_subrange_(struct queue *q, unsigned nr_elts, unsigned lbegin, unsigned lend)
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{
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unsigned level, nr_levels, entries_per_level, remainder;
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BUG_ON(lbegin > lend);
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BUG_ON(lend > q->nr_levels);
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nr_levels = lend - lbegin;
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entries_per_level = safe_div(nr_elts, nr_levels);
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remainder = safe_mod(nr_elts, nr_levels);
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for (level = lbegin; level < lend; level++)
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q->target_count[level] =
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(level < (lbegin + remainder)) ? entries_per_level + 1u : entries_per_level;
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}
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/*
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* Typically we have fewer elements in the top few levels which allows us
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* to adjust the promote threshold nicely.
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*/
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static void q_set_targets(struct queue *q)
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{
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if (q->last_target_nr_elts == q->nr_elts)
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return;
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q->last_target_nr_elts = q->nr_elts;
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if (q->nr_top_levels > q->nr_levels)
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q_set_targets_subrange_(q, q->nr_elts, 0, q->nr_levels);
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else {
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q_set_targets_subrange_(q, q->nr_in_top_levels,
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q->nr_levels - q->nr_top_levels, q->nr_levels);
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if (q->nr_in_top_levels < q->nr_elts)
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q_set_targets_subrange_(q, q->nr_elts - q->nr_in_top_levels,
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0, q->nr_levels - q->nr_top_levels);
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else
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q_set_targets_subrange_(q, 0, 0, q->nr_levels - q->nr_top_levels);
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}
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}
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static void q_redistribute(struct queue *q)
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{
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unsigned target, level;
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struct ilist *l, *l_above;
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struct entry *e;
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q_set_targets(q);
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for (level = 0u; level < q->nr_levels - 1u; level++) {
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l = q->qs + level;
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target = q->target_count[level];
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/*
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* Pull down some entries from the level above.
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*/
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while (l->nr_elts < target) {
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e = __redist_pop_from(q, level + 1u);
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if (!e) {
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/* bug in nr_elts */
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break;
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}
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e->level = level;
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l_add_tail(q->es, l, e);
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}
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/*
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* Push some entries up.
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*/
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l_above = q->qs + level + 1u;
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while (l->nr_elts > target) {
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e = l_pop_tail(q->es, l);
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if (!e)
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/* bug in nr_elts */
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break;
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e->level = level + 1u;
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l_add_tail(q->es, l_above, e);
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}
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}
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}
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static void q_requeue(struct queue *q, struct entry *e, unsigned extra_levels,
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struct entry *s1, struct entry *s2)
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{
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struct entry *de;
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unsigned sentinels_passed = 0;
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unsigned new_level = min(q->nr_levels - 1u, e->level + extra_levels);
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/* try and find an entry to swap with */
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if (extra_levels && (e->level < q->nr_levels - 1u)) {
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for (de = l_head(q->es, q->qs + new_level); de && de->sentinel; de = l_next(q->es, de))
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sentinels_passed++;
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if (de) {
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q_del(q, de);
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de->level = e->level;
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if (s1) {
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switch (sentinels_passed) {
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case 0:
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q_push_before(q, s1, de);
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break;
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case 1:
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q_push_before(q, s2, de);
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break;
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default:
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q_push(q, de);
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}
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} else
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q_push(q, de);
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}
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}
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q_del(q, e);
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e->level = new_level;
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q_push(q, e);
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}
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/*----------------------------------------------------------------*/
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#define FP_SHIFT 8
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#define SIXTEENTH (1u << (FP_SHIFT - 4u))
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#define EIGHTH (1u << (FP_SHIFT - 3u))
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struct stats {
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unsigned hit_threshold;
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unsigned hits;
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unsigned misses;
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};
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enum performance {
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Q_POOR,
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Q_FAIR,
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Q_WELL
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};
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static void stats_init(struct stats *s, unsigned nr_levels)
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{
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s->hit_threshold = (nr_levels * 3u) / 4u;
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s->hits = 0u;
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s->misses = 0u;
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}
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static void stats_reset(struct stats *s)
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{
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s->hits = s->misses = 0u;
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}
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static void stats_level_accessed(struct stats *s, unsigned level)
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{
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if (level >= s->hit_threshold)
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s->hits++;
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else
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s->misses++;
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}
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static void stats_miss(struct stats *s)
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{
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s->misses++;
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}
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/*
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* There are times when we don't have any confidence in the hotspot queue.
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* Such as when a fresh cache is created and the blocks have been spread
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* out across the levels, or if an io load changes. We detect this by
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* seeing how often a lookup is in the top levels of the hotspot queue.
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*/
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static enum performance stats_assess(struct stats *s)
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{
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unsigned confidence = safe_div(s->hits << FP_SHIFT, s->hits + s->misses);
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if (confidence < SIXTEENTH)
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return Q_POOR;
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else if (confidence < EIGHTH)
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return Q_FAIR;
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else
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return Q_WELL;
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}
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/*----------------------------------------------------------------*/
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struct smq_hash_table {
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struct entry_space *es;
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unsigned long long hash_bits;
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unsigned *buckets;
|
|
};
|
|
|
|
/*
|
|
* All cache entries are stored in a chained hash table. To save space we
|
|
* use indexing again, and only store indexes to the next entry.
|
|
*/
|
|
static int h_init(struct smq_hash_table *ht, struct entry_space *es, unsigned nr_entries)
|
|
{
|
|
unsigned i, nr_buckets;
|
|
|
|
ht->es = es;
|
|
nr_buckets = roundup_pow_of_two(max(nr_entries / 4u, 16u));
|
|
ht->hash_bits = __ffs(nr_buckets);
|
|
|
|
ht->buckets = vmalloc(array_size(nr_buckets, sizeof(*ht->buckets)));
|
|
if (!ht->buckets)
|
|
return -ENOMEM;
|
|
|
|
for (i = 0; i < nr_buckets; i++)
|
|
ht->buckets[i] = INDEXER_NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void h_exit(struct smq_hash_table *ht)
|
|
{
|
|
vfree(ht->buckets);
|
|
}
|
|
|
|
static struct entry *h_head(struct smq_hash_table *ht, unsigned bucket)
|
|
{
|
|
return to_entry(ht->es, ht->buckets[bucket]);
|
|
}
|
|
|
|
static struct entry *h_next(struct smq_hash_table *ht, struct entry *e)
|
|
{
|
|
return to_entry(ht->es, e->hash_next);
|
|
}
|
|
|
|
static void __h_insert(struct smq_hash_table *ht, unsigned bucket, struct entry *e)
|
|
{
|
|
e->hash_next = ht->buckets[bucket];
|
|
ht->buckets[bucket] = to_index(ht->es, e);
|
|
}
|
|
|
|
static void h_insert(struct smq_hash_table *ht, struct entry *e)
|
|
{
|
|
unsigned h = hash_64(from_oblock(e->oblock), ht->hash_bits);
|
|
__h_insert(ht, h, e);
|
|
}
|
|
|
|
static struct entry *__h_lookup(struct smq_hash_table *ht, unsigned h, dm_oblock_t oblock,
|
|
struct entry **prev)
|
|
{
|
|
struct entry *e;
|
|
|
|
*prev = NULL;
|
|
for (e = h_head(ht, h); e; e = h_next(ht, e)) {
|
|
if (e->oblock == oblock)
|
|
return e;
|
|
|
|
*prev = e;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void __h_unlink(struct smq_hash_table *ht, unsigned h,
|
|
struct entry *e, struct entry *prev)
|
|
{
|
|
if (prev)
|
|
prev->hash_next = e->hash_next;
|
|
else
|
|
ht->buckets[h] = e->hash_next;
|
|
}
|
|
|
|
/*
|
|
* Also moves each entry to the front of the bucket.
|
|
*/
|
|
static struct entry *h_lookup(struct smq_hash_table *ht, dm_oblock_t oblock)
|
|
{
|
|
struct entry *e, *prev;
|
|
unsigned h = hash_64(from_oblock(oblock), ht->hash_bits);
|
|
|
|
e = __h_lookup(ht, h, oblock, &prev);
|
|
if (e && prev) {
|
|
/*
|
|
* Move to the front because this entry is likely
|
|
* to be hit again.
|
|
*/
|
|
__h_unlink(ht, h, e, prev);
|
|
__h_insert(ht, h, e);
|
|
}
|
|
|
|
return e;
|
|
}
|
|
|
|
static void h_remove(struct smq_hash_table *ht, struct entry *e)
|
|
{
|
|
unsigned h = hash_64(from_oblock(e->oblock), ht->hash_bits);
|
|
struct entry *prev;
|
|
|
|
/*
|
|
* The down side of using a singly linked list is we have to
|
|
* iterate the bucket to remove an item.
|
|
*/
|
|
e = __h_lookup(ht, h, e->oblock, &prev);
|
|
if (e)
|
|
__h_unlink(ht, h, e, prev);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
struct entry_alloc {
|
|
struct entry_space *es;
|
|
unsigned begin;
|
|
|
|
unsigned nr_allocated;
|
|
struct ilist free;
|
|
};
|
|
|
|
static void init_allocator(struct entry_alloc *ea, struct entry_space *es,
|
|
unsigned begin, unsigned end)
|
|
{
|
|
unsigned i;
|
|
|
|
ea->es = es;
|
|
ea->nr_allocated = 0u;
|
|
ea->begin = begin;
|
|
|
|
l_init(&ea->free);
|
|
for (i = begin; i != end; i++)
|
|
l_add_tail(ea->es, &ea->free, __get_entry(ea->es, i));
|
|
}
|
|
|
|
static void init_entry(struct entry *e)
|
|
{
|
|
/*
|
|
* We can't memset because that would clear the hotspot and
|
|
* sentinel bits which remain constant.
|
|
*/
|
|
e->hash_next = INDEXER_NULL;
|
|
e->next = INDEXER_NULL;
|
|
e->prev = INDEXER_NULL;
|
|
e->level = 0u;
|
|
e->dirty = true; /* FIXME: audit */
|
|
e->allocated = true;
|
|
e->sentinel = false;
|
|
e->pending_work = false;
|
|
}
|
|
|
|
static struct entry *alloc_entry(struct entry_alloc *ea)
|
|
{
|
|
struct entry *e;
|
|
|
|
if (l_empty(&ea->free))
|
|
return NULL;
|
|
|
|
e = l_pop_head(ea->es, &ea->free);
|
|
init_entry(e);
|
|
ea->nr_allocated++;
|
|
|
|
return e;
|
|
}
|
|
|
|
/*
|
|
* This assumes the cblock hasn't already been allocated.
|
|
*/
|
|
static struct entry *alloc_particular_entry(struct entry_alloc *ea, unsigned i)
|
|
{
|
|
struct entry *e = __get_entry(ea->es, ea->begin + i);
|
|
|
|
BUG_ON(e->allocated);
|
|
|
|
l_del(ea->es, &ea->free, e);
|
|
init_entry(e);
|
|
ea->nr_allocated++;
|
|
|
|
return e;
|
|
}
|
|
|
|
static void free_entry(struct entry_alloc *ea, struct entry *e)
|
|
{
|
|
BUG_ON(!ea->nr_allocated);
|
|
BUG_ON(!e->allocated);
|
|
|
|
ea->nr_allocated--;
|
|
e->allocated = false;
|
|
l_add_tail(ea->es, &ea->free, e);
|
|
}
|
|
|
|
static bool allocator_empty(struct entry_alloc *ea)
|
|
{
|
|
return l_empty(&ea->free);
|
|
}
|
|
|
|
static unsigned get_index(struct entry_alloc *ea, struct entry *e)
|
|
{
|
|
return to_index(ea->es, e) - ea->begin;
|
|
}
|
|
|
|
static struct entry *get_entry(struct entry_alloc *ea, unsigned index)
|
|
{
|
|
return __get_entry(ea->es, ea->begin + index);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
#define NR_HOTSPOT_LEVELS 64u
|
|
#define NR_CACHE_LEVELS 64u
|
|
|
|
#define WRITEBACK_PERIOD (10ul * HZ)
|
|
#define DEMOTE_PERIOD (60ul * HZ)
|
|
|
|
#define HOTSPOT_UPDATE_PERIOD (HZ)
|
|
#define CACHE_UPDATE_PERIOD (60ul * HZ)
|
|
|
|
struct smq_policy {
|
|
struct dm_cache_policy policy;
|
|
|
|
/* protects everything */
|
|
spinlock_t lock;
|
|
dm_cblock_t cache_size;
|
|
sector_t cache_block_size;
|
|
|
|
sector_t hotspot_block_size;
|
|
unsigned nr_hotspot_blocks;
|
|
unsigned cache_blocks_per_hotspot_block;
|
|
unsigned hotspot_level_jump;
|
|
|
|
struct entry_space es;
|
|
struct entry_alloc writeback_sentinel_alloc;
|
|
struct entry_alloc demote_sentinel_alloc;
|
|
struct entry_alloc hotspot_alloc;
|
|
struct entry_alloc cache_alloc;
|
|
|
|
unsigned long *hotspot_hit_bits;
|
|
unsigned long *cache_hit_bits;
|
|
|
|
/*
|
|
* We maintain three queues of entries. The cache proper,
|
|
* consisting of a clean and dirty queue, containing the currently
|
|
* active mappings. The hotspot queue uses a larger block size to
|
|
* track blocks that are being hit frequently and potential
|
|
* candidates for promotion to the cache.
|
|
*/
|
|
struct queue hotspot;
|
|
struct queue clean;
|
|
struct queue dirty;
|
|
|
|
struct stats hotspot_stats;
|
|
struct stats cache_stats;
|
|
|
|
/*
|
|
* Keeps track of time, incremented by the core. We use this to
|
|
* avoid attributing multiple hits within the same tick.
|
|
*/
|
|
unsigned tick;
|
|
|
|
/*
|
|
* The hash tables allows us to quickly find an entry by origin
|
|
* block.
|
|
*/
|
|
struct smq_hash_table table;
|
|
struct smq_hash_table hotspot_table;
|
|
|
|
bool current_writeback_sentinels;
|
|
unsigned long next_writeback_period;
|
|
|
|
bool current_demote_sentinels;
|
|
unsigned long next_demote_period;
|
|
|
|
unsigned write_promote_level;
|
|
unsigned read_promote_level;
|
|
|
|
unsigned long next_hotspot_period;
|
|
unsigned long next_cache_period;
|
|
|
|
struct background_tracker *bg_work;
|
|
|
|
bool migrations_allowed;
|
|
};
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static struct entry *get_sentinel(struct entry_alloc *ea, unsigned level, bool which)
|
|
{
|
|
return get_entry(ea, which ? level : NR_CACHE_LEVELS + level);
|
|
}
|
|
|
|
static struct entry *writeback_sentinel(struct smq_policy *mq, unsigned level)
|
|
{
|
|
return get_sentinel(&mq->writeback_sentinel_alloc, level, mq->current_writeback_sentinels);
|
|
}
|
|
|
|
static struct entry *demote_sentinel(struct smq_policy *mq, unsigned level)
|
|
{
|
|
return get_sentinel(&mq->demote_sentinel_alloc, level, mq->current_demote_sentinels);
|
|
}
|
|
|
|
static void __update_writeback_sentinels(struct smq_policy *mq)
|
|
{
|
|
unsigned level;
|
|
struct queue *q = &mq->dirty;
|
|
struct entry *sentinel;
|
|
|
|
for (level = 0; level < q->nr_levels; level++) {
|
|
sentinel = writeback_sentinel(mq, level);
|
|
q_del(q, sentinel);
|
|
q_push(q, sentinel);
|
|
}
|
|
}
|
|
|
|
static void __update_demote_sentinels(struct smq_policy *mq)
|
|
{
|
|
unsigned level;
|
|
struct queue *q = &mq->clean;
|
|
struct entry *sentinel;
|
|
|
|
for (level = 0; level < q->nr_levels; level++) {
|
|
sentinel = demote_sentinel(mq, level);
|
|
q_del(q, sentinel);
|
|
q_push(q, sentinel);
|
|
}
|
|
}
|
|
|
|
static void update_sentinels(struct smq_policy *mq)
|
|
{
|
|
if (time_after(jiffies, mq->next_writeback_period)) {
|
|
mq->next_writeback_period = jiffies + WRITEBACK_PERIOD;
|
|
mq->current_writeback_sentinels = !mq->current_writeback_sentinels;
|
|
__update_writeback_sentinels(mq);
|
|
}
|
|
|
|
if (time_after(jiffies, mq->next_demote_period)) {
|
|
mq->next_demote_period = jiffies + DEMOTE_PERIOD;
|
|
mq->current_demote_sentinels = !mq->current_demote_sentinels;
|
|
__update_demote_sentinels(mq);
|
|
}
|
|
}
|
|
|
|
static void __sentinels_init(struct smq_policy *mq)
|
|
{
|
|
unsigned level;
|
|
struct entry *sentinel;
|
|
|
|
for (level = 0; level < NR_CACHE_LEVELS; level++) {
|
|
sentinel = writeback_sentinel(mq, level);
|
|
sentinel->level = level;
|
|
q_push(&mq->dirty, sentinel);
|
|
|
|
sentinel = demote_sentinel(mq, level);
|
|
sentinel->level = level;
|
|
q_push(&mq->clean, sentinel);
|
|
}
|
|
}
|
|
|
|
static void sentinels_init(struct smq_policy *mq)
|
|
{
|
|
mq->next_writeback_period = jiffies + WRITEBACK_PERIOD;
|
|
mq->next_demote_period = jiffies + DEMOTE_PERIOD;
|
|
|
|
mq->current_writeback_sentinels = false;
|
|
mq->current_demote_sentinels = false;
|
|
__sentinels_init(mq);
|
|
|
|
mq->current_writeback_sentinels = !mq->current_writeback_sentinels;
|
|
mq->current_demote_sentinels = !mq->current_demote_sentinels;
|
|
__sentinels_init(mq);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void del_queue(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
q_del(e->dirty ? &mq->dirty : &mq->clean, e);
|
|
}
|
|
|
|
static void push_queue(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
if (e->dirty)
|
|
q_push(&mq->dirty, e);
|
|
else
|
|
q_push(&mq->clean, e);
|
|
}
|
|
|
|
// !h, !q, a -> h, q, a
|
|
static void push(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
h_insert(&mq->table, e);
|
|
if (!e->pending_work)
|
|
push_queue(mq, e);
|
|
}
|
|
|
|
static void push_queue_front(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
if (e->dirty)
|
|
q_push_front(&mq->dirty, e);
|
|
else
|
|
q_push_front(&mq->clean, e);
|
|
}
|
|
|
|
static void push_front(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
h_insert(&mq->table, e);
|
|
if (!e->pending_work)
|
|
push_queue_front(mq, e);
|
|
}
|
|
|
|
static dm_cblock_t infer_cblock(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
return to_cblock(get_index(&mq->cache_alloc, e));
|
|
}
|
|
|
|
static void requeue(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
/*
|
|
* Pending work has temporarily been taken out of the queues.
|
|
*/
|
|
if (e->pending_work)
|
|
return;
|
|
|
|
if (!test_and_set_bit(from_cblock(infer_cblock(mq, e)), mq->cache_hit_bits)) {
|
|
if (!e->dirty) {
|
|
q_requeue(&mq->clean, e, 1u, NULL, NULL);
|
|
return;
|
|
}
|
|
|
|
q_requeue(&mq->dirty, e, 1u,
|
|
get_sentinel(&mq->writeback_sentinel_alloc, e->level, !mq->current_writeback_sentinels),
|
|
get_sentinel(&mq->writeback_sentinel_alloc, e->level, mq->current_writeback_sentinels));
|
|
}
|
|
}
|
|
|
|
static unsigned default_promote_level(struct smq_policy *mq)
|
|
{
|
|
/*
|
|
* The promote level depends on the current performance of the
|
|
* cache.
|
|
*
|
|
* If the cache is performing badly, then we can't afford
|
|
* to promote much without causing performance to drop below that
|
|
* of the origin device.
|
|
*
|
|
* If the cache is performing well, then we don't need to promote
|
|
* much. If it isn't broken, don't fix it.
|
|
*
|
|
* If the cache is middling then we promote more.
|
|
*
|
|
* This scheme reminds me of a graph of entropy vs probability of a
|
|
* binary variable.
|
|
*/
|
|
static unsigned table[] = {1, 1, 1, 2, 4, 6, 7, 8, 7, 6, 4, 4, 3, 3, 2, 2, 1};
|
|
|
|
unsigned hits = mq->cache_stats.hits;
|
|
unsigned misses = mq->cache_stats.misses;
|
|
unsigned index = safe_div(hits << 4u, hits + misses);
|
|
return table[index];
|
|
}
|
|
|
|
static void update_promote_levels(struct smq_policy *mq)
|
|
{
|
|
/*
|
|
* If there are unused cache entries then we want to be really
|
|
* eager to promote.
|
|
*/
|
|
unsigned threshold_level = allocator_empty(&mq->cache_alloc) ?
|
|
default_promote_level(mq) : (NR_HOTSPOT_LEVELS / 2u);
|
|
|
|
threshold_level = max(threshold_level, NR_HOTSPOT_LEVELS);
|
|
|
|
/*
|
|
* If the hotspot queue is performing badly then we have little
|
|
* confidence that we know which blocks to promote. So we cut down
|
|
* the amount of promotions.
|
|
*/
|
|
switch (stats_assess(&mq->hotspot_stats)) {
|
|
case Q_POOR:
|
|
threshold_level /= 4u;
|
|
break;
|
|
|
|
case Q_FAIR:
|
|
threshold_level /= 2u;
|
|
break;
|
|
|
|
case Q_WELL:
|
|
break;
|
|
}
|
|
|
|
mq->read_promote_level = NR_HOTSPOT_LEVELS - threshold_level;
|
|
mq->write_promote_level = (NR_HOTSPOT_LEVELS - threshold_level);
|
|
}
|
|
|
|
/*
|
|
* If the hotspot queue is performing badly, then we try and move entries
|
|
* around more quickly.
|
|
*/
|
|
static void update_level_jump(struct smq_policy *mq)
|
|
{
|
|
switch (stats_assess(&mq->hotspot_stats)) {
|
|
case Q_POOR:
|
|
mq->hotspot_level_jump = 4u;
|
|
break;
|
|
|
|
case Q_FAIR:
|
|
mq->hotspot_level_jump = 2u;
|
|
break;
|
|
|
|
case Q_WELL:
|
|
mq->hotspot_level_jump = 1u;
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void end_hotspot_period(struct smq_policy *mq)
|
|
{
|
|
clear_bitset(mq->hotspot_hit_bits, mq->nr_hotspot_blocks);
|
|
update_promote_levels(mq);
|
|
|
|
if (time_after(jiffies, mq->next_hotspot_period)) {
|
|
update_level_jump(mq);
|
|
q_redistribute(&mq->hotspot);
|
|
stats_reset(&mq->hotspot_stats);
|
|
mq->next_hotspot_period = jiffies + HOTSPOT_UPDATE_PERIOD;
|
|
}
|
|
}
|
|
|
|
static void end_cache_period(struct smq_policy *mq)
|
|
{
|
|
if (time_after(jiffies, mq->next_cache_period)) {
|
|
clear_bitset(mq->cache_hit_bits, from_cblock(mq->cache_size));
|
|
|
|
q_redistribute(&mq->dirty);
|
|
q_redistribute(&mq->clean);
|
|
stats_reset(&mq->cache_stats);
|
|
|
|
mq->next_cache_period = jiffies + CACHE_UPDATE_PERIOD;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Targets are given as a percentage.
|
|
*/
|
|
#define CLEAN_TARGET 25u
|
|
#define FREE_TARGET 25u
|
|
|
|
static unsigned percent_to_target(struct smq_policy *mq, unsigned p)
|
|
{
|
|
return from_cblock(mq->cache_size) * p / 100u;
|
|
}
|
|
|
|
static bool clean_target_met(struct smq_policy *mq, bool idle)
|
|
{
|
|
/*
|
|
* Cache entries may not be populated. So we cannot rely on the
|
|
* size of the clean queue.
|
|
*/
|
|
if (idle) {
|
|
/*
|
|
* We'd like to clean everything.
|
|
*/
|
|
return q_size(&mq->dirty) == 0u;
|
|
}
|
|
|
|
/*
|
|
* If we're busy we don't worry about cleaning at all.
|
|
*/
|
|
return true;
|
|
}
|
|
|
|
static bool free_target_met(struct smq_policy *mq)
|
|
{
|
|
unsigned nr_free;
|
|
|
|
nr_free = from_cblock(mq->cache_size) - mq->cache_alloc.nr_allocated;
|
|
return (nr_free + btracker_nr_demotions_queued(mq->bg_work)) >=
|
|
percent_to_target(mq, FREE_TARGET);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void mark_pending(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
BUG_ON(e->sentinel);
|
|
BUG_ON(!e->allocated);
|
|
BUG_ON(e->pending_work);
|
|
e->pending_work = true;
|
|
}
|
|
|
|
static void clear_pending(struct smq_policy *mq, struct entry *e)
|
|
{
|
|
BUG_ON(!e->pending_work);
|
|
e->pending_work = false;
|
|
}
|
|
|
|
static void queue_writeback(struct smq_policy *mq, bool idle)
|
|
{
|
|
int r;
|
|
struct policy_work work;
|
|
struct entry *e;
|
|
|
|
e = q_peek(&mq->dirty, mq->dirty.nr_levels, idle);
|
|
if (e) {
|
|
mark_pending(mq, e);
|
|
q_del(&mq->dirty, e);
|
|
|
|
work.op = POLICY_WRITEBACK;
|
|
work.oblock = e->oblock;
|
|
work.cblock = infer_cblock(mq, e);
|
|
|
|
r = btracker_queue(mq->bg_work, &work, NULL);
|
|
if (r) {
|
|
clear_pending(mq, e);
|
|
q_push_front(&mq->dirty, e);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void queue_demotion(struct smq_policy *mq)
|
|
{
|
|
int r;
|
|
struct policy_work work;
|
|
struct entry *e;
|
|
|
|
if (WARN_ON_ONCE(!mq->migrations_allowed))
|
|
return;
|
|
|
|
e = q_peek(&mq->clean, mq->clean.nr_levels / 2, true);
|
|
if (!e) {
|
|
if (!clean_target_met(mq, true))
|
|
queue_writeback(mq, false);
|
|
return;
|
|
}
|
|
|
|
mark_pending(mq, e);
|
|
q_del(&mq->clean, e);
|
|
|
|
work.op = POLICY_DEMOTE;
|
|
work.oblock = e->oblock;
|
|
work.cblock = infer_cblock(mq, e);
|
|
r = btracker_queue(mq->bg_work, &work, NULL);
|
|
if (r) {
|
|
clear_pending(mq, e);
|
|
q_push_front(&mq->clean, e);
|
|
}
|
|
}
|
|
|
|
static void queue_promotion(struct smq_policy *mq, dm_oblock_t oblock,
|
|
struct policy_work **workp)
|
|
{
|
|
int r;
|
|
struct entry *e;
|
|
struct policy_work work;
|
|
|
|
if (!mq->migrations_allowed)
|
|
return;
|
|
|
|
if (allocator_empty(&mq->cache_alloc)) {
|
|
/*
|
|
* We always claim to be 'idle' to ensure some demotions happen
|
|
* with continuous loads.
|
|
*/
|
|
if (!free_target_met(mq))
|
|
queue_demotion(mq);
|
|
return;
|
|
}
|
|
|
|
if (btracker_promotion_already_present(mq->bg_work, oblock))
|
|
return;
|
|
|
|
/*
|
|
* We allocate the entry now to reserve the cblock. If the
|
|
* background work is aborted we must remember to free it.
|
|
*/
|
|
e = alloc_entry(&mq->cache_alloc);
|
|
BUG_ON(!e);
|
|
e->pending_work = true;
|
|
work.op = POLICY_PROMOTE;
|
|
work.oblock = oblock;
|
|
work.cblock = infer_cblock(mq, e);
|
|
r = btracker_queue(mq->bg_work, &work, workp);
|
|
if (r)
|
|
free_entry(&mq->cache_alloc, e);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
enum promote_result {
|
|
PROMOTE_NOT,
|
|
PROMOTE_TEMPORARY,
|
|
PROMOTE_PERMANENT
|
|
};
|
|
|
|
/*
|
|
* Converts a boolean into a promote result.
|
|
*/
|
|
static enum promote_result maybe_promote(bool promote)
|
|
{
|
|
return promote ? PROMOTE_PERMANENT : PROMOTE_NOT;
|
|
}
|
|
|
|
static enum promote_result should_promote(struct smq_policy *mq, struct entry *hs_e,
|
|
int data_dir, bool fast_promote)
|
|
{
|
|
if (data_dir == WRITE) {
|
|
if (!allocator_empty(&mq->cache_alloc) && fast_promote)
|
|
return PROMOTE_TEMPORARY;
|
|
|
|
return maybe_promote(hs_e->level >= mq->write_promote_level);
|
|
} else
|
|
return maybe_promote(hs_e->level >= mq->read_promote_level);
|
|
}
|
|
|
|
static dm_oblock_t to_hblock(struct smq_policy *mq, dm_oblock_t b)
|
|
{
|
|
sector_t r = from_oblock(b);
|
|
(void) sector_div(r, mq->cache_blocks_per_hotspot_block);
|
|
return to_oblock(r);
|
|
}
|
|
|
|
static struct entry *update_hotspot_queue(struct smq_policy *mq, dm_oblock_t b)
|
|
{
|
|
unsigned hi;
|
|
dm_oblock_t hb = to_hblock(mq, b);
|
|
struct entry *e = h_lookup(&mq->hotspot_table, hb);
|
|
|
|
if (e) {
|
|
stats_level_accessed(&mq->hotspot_stats, e->level);
|
|
|
|
hi = get_index(&mq->hotspot_alloc, e);
|
|
q_requeue(&mq->hotspot, e,
|
|
test_and_set_bit(hi, mq->hotspot_hit_bits) ?
|
|
0u : mq->hotspot_level_jump,
|
|
NULL, NULL);
|
|
|
|
} else {
|
|
stats_miss(&mq->hotspot_stats);
|
|
|
|
e = alloc_entry(&mq->hotspot_alloc);
|
|
if (!e) {
|
|
e = q_pop(&mq->hotspot);
|
|
if (e) {
|
|
h_remove(&mq->hotspot_table, e);
|
|
hi = get_index(&mq->hotspot_alloc, e);
|
|
clear_bit(hi, mq->hotspot_hit_bits);
|
|
}
|
|
|
|
}
|
|
|
|
if (e) {
|
|
e->oblock = hb;
|
|
q_push(&mq->hotspot, e);
|
|
h_insert(&mq->hotspot_table, e);
|
|
}
|
|
}
|
|
|
|
return e;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Public interface, via the policy struct. See dm-cache-policy.h for a
|
|
* description of these.
|
|
*/
|
|
|
|
static struct smq_policy *to_smq_policy(struct dm_cache_policy *p)
|
|
{
|
|
return container_of(p, struct smq_policy, policy);
|
|
}
|
|
|
|
static void smq_destroy(struct dm_cache_policy *p)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
btracker_destroy(mq->bg_work);
|
|
h_exit(&mq->hotspot_table);
|
|
h_exit(&mq->table);
|
|
free_bitset(mq->hotspot_hit_bits);
|
|
free_bitset(mq->cache_hit_bits);
|
|
space_exit(&mq->es);
|
|
kfree(mq);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static int __lookup(struct smq_policy *mq, dm_oblock_t oblock, dm_cblock_t *cblock,
|
|
int data_dir, bool fast_copy,
|
|
struct policy_work **work, bool *background_work)
|
|
{
|
|
struct entry *e, *hs_e;
|
|
enum promote_result pr;
|
|
|
|
*background_work = false;
|
|
|
|
e = h_lookup(&mq->table, oblock);
|
|
if (e) {
|
|
stats_level_accessed(&mq->cache_stats, e->level);
|
|
|
|
requeue(mq, e);
|
|
*cblock = infer_cblock(mq, e);
|
|
return 0;
|
|
|
|
} else {
|
|
stats_miss(&mq->cache_stats);
|
|
|
|
/*
|
|
* The hotspot queue only gets updated with misses.
|
|
*/
|
|
hs_e = update_hotspot_queue(mq, oblock);
|
|
|
|
pr = should_promote(mq, hs_e, data_dir, fast_copy);
|
|
if (pr != PROMOTE_NOT) {
|
|
queue_promotion(mq, oblock, work);
|
|
*background_work = true;
|
|
}
|
|
|
|
return -ENOENT;
|
|
}
|
|
}
|
|
|
|
static int smq_lookup(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock,
|
|
int data_dir, bool fast_copy,
|
|
bool *background_work)
|
|
{
|
|
int r;
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
r = __lookup(mq, oblock, cblock,
|
|
data_dir, fast_copy,
|
|
NULL, background_work);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
static int smq_lookup_with_work(struct dm_cache_policy *p,
|
|
dm_oblock_t oblock, dm_cblock_t *cblock,
|
|
int data_dir, bool fast_copy,
|
|
struct policy_work **work)
|
|
{
|
|
int r;
|
|
bool background_queued;
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
r = __lookup(mq, oblock, cblock, data_dir, fast_copy, work, &background_queued);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
static int smq_get_background_work(struct dm_cache_policy *p, bool idle,
|
|
struct policy_work **result)
|
|
{
|
|
int r;
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
r = btracker_issue(mq->bg_work, result);
|
|
if (r == -ENODATA) {
|
|
if (!clean_target_met(mq, idle)) {
|
|
queue_writeback(mq, idle);
|
|
r = btracker_issue(mq->bg_work, result);
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* We need to clear any pending work flags that have been set, and in the
|
|
* case of promotion free the entry for the destination cblock.
|
|
*/
|
|
static void __complete_background_work(struct smq_policy *mq,
|
|
struct policy_work *work,
|
|
bool success)
|
|
{
|
|
struct entry *e = get_entry(&mq->cache_alloc,
|
|
from_cblock(work->cblock));
|
|
|
|
switch (work->op) {
|
|
case POLICY_PROMOTE:
|
|
// !h, !q, a
|
|
clear_pending(mq, e);
|
|
if (success) {
|
|
e->oblock = work->oblock;
|
|
e->level = NR_CACHE_LEVELS - 1;
|
|
push(mq, e);
|
|
// h, q, a
|
|
} else {
|
|
free_entry(&mq->cache_alloc, e);
|
|
// !h, !q, !a
|
|
}
|
|
break;
|
|
|
|
case POLICY_DEMOTE:
|
|
// h, !q, a
|
|
if (success) {
|
|
h_remove(&mq->table, e);
|
|
free_entry(&mq->cache_alloc, e);
|
|
// !h, !q, !a
|
|
} else {
|
|
clear_pending(mq, e);
|
|
push_queue(mq, e);
|
|
// h, q, a
|
|
}
|
|
break;
|
|
|
|
case POLICY_WRITEBACK:
|
|
// h, !q, a
|
|
clear_pending(mq, e);
|
|
push_queue(mq, e);
|
|
// h, q, a
|
|
break;
|
|
}
|
|
|
|
btracker_complete(mq->bg_work, work);
|
|
}
|
|
|
|
static void smq_complete_background_work(struct dm_cache_policy *p,
|
|
struct policy_work *work,
|
|
bool success)
|
|
{
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
__complete_background_work(mq, work, success);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
}
|
|
|
|
// in_hash(oblock) -> in_hash(oblock)
|
|
static void __smq_set_clear_dirty(struct smq_policy *mq, dm_cblock_t cblock, bool set)
|
|
{
|
|
struct entry *e = get_entry(&mq->cache_alloc, from_cblock(cblock));
|
|
|
|
if (e->pending_work)
|
|
e->dirty = set;
|
|
else {
|
|
del_queue(mq, e);
|
|
e->dirty = set;
|
|
push_queue(mq, e);
|
|
}
|
|
}
|
|
|
|
static void smq_set_dirty(struct dm_cache_policy *p, dm_cblock_t cblock)
|
|
{
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
__smq_set_clear_dirty(mq, cblock, true);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
}
|
|
|
|
static void smq_clear_dirty(struct dm_cache_policy *p, dm_cblock_t cblock)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
__smq_set_clear_dirty(mq, cblock, false);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
}
|
|
|
|
static unsigned random_level(dm_cblock_t cblock)
|
|
{
|
|
return hash_32(from_cblock(cblock), 9) & (NR_CACHE_LEVELS - 1);
|
|
}
|
|
|
|
static int smq_load_mapping(struct dm_cache_policy *p,
|
|
dm_oblock_t oblock, dm_cblock_t cblock,
|
|
bool dirty, uint32_t hint, bool hint_valid)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
struct entry *e;
|
|
|
|
e = alloc_particular_entry(&mq->cache_alloc, from_cblock(cblock));
|
|
e->oblock = oblock;
|
|
e->dirty = dirty;
|
|
e->level = hint_valid ? min(hint, NR_CACHE_LEVELS - 1) : random_level(cblock);
|
|
e->pending_work = false;
|
|
|
|
/*
|
|
* When we load mappings we push ahead of both sentinels in order to
|
|
* allow demotions and cleaning to occur immediately.
|
|
*/
|
|
push_front(mq, e);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int smq_invalidate_mapping(struct dm_cache_policy *p, dm_cblock_t cblock)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
struct entry *e = get_entry(&mq->cache_alloc, from_cblock(cblock));
|
|
|
|
if (!e->allocated)
|
|
return -ENODATA;
|
|
|
|
// FIXME: what if this block has pending background work?
|
|
del_queue(mq, e);
|
|
h_remove(&mq->table, e);
|
|
free_entry(&mq->cache_alloc, e);
|
|
return 0;
|
|
}
|
|
|
|
static uint32_t smq_get_hint(struct dm_cache_policy *p, dm_cblock_t cblock)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
struct entry *e = get_entry(&mq->cache_alloc, from_cblock(cblock));
|
|
|
|
if (!e->allocated)
|
|
return 0;
|
|
|
|
return e->level;
|
|
}
|
|
|
|
static dm_cblock_t smq_residency(struct dm_cache_policy *p)
|
|
{
|
|
dm_cblock_t r;
|
|
unsigned long flags;
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
r = to_cblock(mq->cache_alloc.nr_allocated);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
static void smq_tick(struct dm_cache_policy *p, bool can_block)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&mq->lock, flags);
|
|
mq->tick++;
|
|
update_sentinels(mq);
|
|
end_hotspot_period(mq);
|
|
end_cache_period(mq);
|
|
spin_unlock_irqrestore(&mq->lock, flags);
|
|
}
|
|
|
|
static void smq_allow_migrations(struct dm_cache_policy *p, bool allow)
|
|
{
|
|
struct smq_policy *mq = to_smq_policy(p);
|
|
mq->migrations_allowed = allow;
|
|
}
|
|
|
|
/*
|
|
* smq has no config values, but the old mq policy did. To avoid breaking
|
|
* software we continue to accept these configurables for the mq policy,
|
|
* but they have no effect.
|
|
*/
|
|
static int mq_set_config_value(struct dm_cache_policy *p,
|
|
const char *key, const char *value)
|
|
{
|
|
unsigned long tmp;
|
|
|
|
if (kstrtoul(value, 10, &tmp))
|
|
return -EINVAL;
|
|
|
|
if (!strcasecmp(key, "random_threshold") ||
|
|
!strcasecmp(key, "sequential_threshold") ||
|
|
!strcasecmp(key, "discard_promote_adjustment") ||
|
|
!strcasecmp(key, "read_promote_adjustment") ||
|
|
!strcasecmp(key, "write_promote_adjustment")) {
|
|
DMWARN("tunable '%s' no longer has any effect, mq policy is now an alias for smq", key);
|
|
return 0;
|
|
}
|
|
|
|
return -EINVAL;
|
|
}
|
|
|
|
static int mq_emit_config_values(struct dm_cache_policy *p, char *result,
|
|
unsigned maxlen, ssize_t *sz_ptr)
|
|
{
|
|
ssize_t sz = *sz_ptr;
|
|
|
|
DMEMIT("10 random_threshold 0 "
|
|
"sequential_threshold 0 "
|
|
"discard_promote_adjustment 0 "
|
|
"read_promote_adjustment 0 "
|
|
"write_promote_adjustment 0 ");
|
|
|
|
*sz_ptr = sz;
|
|
return 0;
|
|
}
|
|
|
|
/* Init the policy plugin interface function pointers. */
|
|
static void init_policy_functions(struct smq_policy *mq, bool mimic_mq)
|
|
{
|
|
mq->policy.destroy = smq_destroy;
|
|
mq->policy.lookup = smq_lookup;
|
|
mq->policy.lookup_with_work = smq_lookup_with_work;
|
|
mq->policy.get_background_work = smq_get_background_work;
|
|
mq->policy.complete_background_work = smq_complete_background_work;
|
|
mq->policy.set_dirty = smq_set_dirty;
|
|
mq->policy.clear_dirty = smq_clear_dirty;
|
|
mq->policy.load_mapping = smq_load_mapping;
|
|
mq->policy.invalidate_mapping = smq_invalidate_mapping;
|
|
mq->policy.get_hint = smq_get_hint;
|
|
mq->policy.residency = smq_residency;
|
|
mq->policy.tick = smq_tick;
|
|
mq->policy.allow_migrations = smq_allow_migrations;
|
|
|
|
if (mimic_mq) {
|
|
mq->policy.set_config_value = mq_set_config_value;
|
|
mq->policy.emit_config_values = mq_emit_config_values;
|
|
}
|
|
}
|
|
|
|
static bool too_many_hotspot_blocks(sector_t origin_size,
|
|
sector_t hotspot_block_size,
|
|
unsigned nr_hotspot_blocks)
|
|
{
|
|
return (hotspot_block_size * nr_hotspot_blocks) > origin_size;
|
|
}
|
|
|
|
static void calc_hotspot_params(sector_t origin_size,
|
|
sector_t cache_block_size,
|
|
unsigned nr_cache_blocks,
|
|
sector_t *hotspot_block_size,
|
|
unsigned *nr_hotspot_blocks)
|
|
{
|
|
*hotspot_block_size = cache_block_size * 16u;
|
|
*nr_hotspot_blocks = max(nr_cache_blocks / 4u, 1024u);
|
|
|
|
while ((*hotspot_block_size > cache_block_size) &&
|
|
too_many_hotspot_blocks(origin_size, *hotspot_block_size, *nr_hotspot_blocks))
|
|
*hotspot_block_size /= 2u;
|
|
}
|
|
|
|
static struct dm_cache_policy *__smq_create(dm_cblock_t cache_size,
|
|
sector_t origin_size,
|
|
sector_t cache_block_size,
|
|
bool mimic_mq,
|
|
bool migrations_allowed)
|
|
{
|
|
unsigned i;
|
|
unsigned nr_sentinels_per_queue = 2u * NR_CACHE_LEVELS;
|
|
unsigned total_sentinels = 2u * nr_sentinels_per_queue;
|
|
struct smq_policy *mq = kzalloc(sizeof(*mq), GFP_KERNEL);
|
|
|
|
if (!mq)
|
|
return NULL;
|
|
|
|
init_policy_functions(mq, mimic_mq);
|
|
mq->cache_size = cache_size;
|
|
mq->cache_block_size = cache_block_size;
|
|
|
|
calc_hotspot_params(origin_size, cache_block_size, from_cblock(cache_size),
|
|
&mq->hotspot_block_size, &mq->nr_hotspot_blocks);
|
|
|
|
mq->cache_blocks_per_hotspot_block = div64_u64(mq->hotspot_block_size, mq->cache_block_size);
|
|
mq->hotspot_level_jump = 1u;
|
|
if (space_init(&mq->es, total_sentinels + mq->nr_hotspot_blocks + from_cblock(cache_size))) {
|
|
DMERR("couldn't initialize entry space");
|
|
goto bad_pool_init;
|
|
}
|
|
|
|
init_allocator(&mq->writeback_sentinel_alloc, &mq->es, 0, nr_sentinels_per_queue);
|
|
for (i = 0; i < nr_sentinels_per_queue; i++)
|
|
get_entry(&mq->writeback_sentinel_alloc, i)->sentinel = true;
|
|
|
|
init_allocator(&mq->demote_sentinel_alloc, &mq->es, nr_sentinels_per_queue, total_sentinels);
|
|
for (i = 0; i < nr_sentinels_per_queue; i++)
|
|
get_entry(&mq->demote_sentinel_alloc, i)->sentinel = true;
|
|
|
|
init_allocator(&mq->hotspot_alloc, &mq->es, total_sentinels,
|
|
total_sentinels + mq->nr_hotspot_blocks);
|
|
|
|
init_allocator(&mq->cache_alloc, &mq->es,
|
|
total_sentinels + mq->nr_hotspot_blocks,
|
|
total_sentinels + mq->nr_hotspot_blocks + from_cblock(cache_size));
|
|
|
|
mq->hotspot_hit_bits = alloc_bitset(mq->nr_hotspot_blocks);
|
|
if (!mq->hotspot_hit_bits) {
|
|
DMERR("couldn't allocate hotspot hit bitset");
|
|
goto bad_hotspot_hit_bits;
|
|
}
|
|
clear_bitset(mq->hotspot_hit_bits, mq->nr_hotspot_blocks);
|
|
|
|
if (from_cblock(cache_size)) {
|
|
mq->cache_hit_bits = alloc_bitset(from_cblock(cache_size));
|
|
if (!mq->cache_hit_bits) {
|
|
DMERR("couldn't allocate cache hit bitset");
|
|
goto bad_cache_hit_bits;
|
|
}
|
|
clear_bitset(mq->cache_hit_bits, from_cblock(mq->cache_size));
|
|
} else
|
|
mq->cache_hit_bits = NULL;
|
|
|
|
mq->tick = 0;
|
|
spin_lock_init(&mq->lock);
|
|
|
|
q_init(&mq->hotspot, &mq->es, NR_HOTSPOT_LEVELS);
|
|
mq->hotspot.nr_top_levels = 8;
|
|
mq->hotspot.nr_in_top_levels = min(mq->nr_hotspot_blocks / NR_HOTSPOT_LEVELS,
|
|
from_cblock(mq->cache_size) / mq->cache_blocks_per_hotspot_block);
|
|
|
|
q_init(&mq->clean, &mq->es, NR_CACHE_LEVELS);
|
|
q_init(&mq->dirty, &mq->es, NR_CACHE_LEVELS);
|
|
|
|
stats_init(&mq->hotspot_stats, NR_HOTSPOT_LEVELS);
|
|
stats_init(&mq->cache_stats, NR_CACHE_LEVELS);
|
|
|
|
if (h_init(&mq->table, &mq->es, from_cblock(cache_size)))
|
|
goto bad_alloc_table;
|
|
|
|
if (h_init(&mq->hotspot_table, &mq->es, mq->nr_hotspot_blocks))
|
|
goto bad_alloc_hotspot_table;
|
|
|
|
sentinels_init(mq);
|
|
mq->write_promote_level = mq->read_promote_level = NR_HOTSPOT_LEVELS;
|
|
|
|
mq->next_hotspot_period = jiffies;
|
|
mq->next_cache_period = jiffies;
|
|
|
|
mq->bg_work = btracker_create(4096); /* FIXME: hard coded value */
|
|
if (!mq->bg_work)
|
|
goto bad_btracker;
|
|
|
|
mq->migrations_allowed = migrations_allowed;
|
|
|
|
return &mq->policy;
|
|
|
|
bad_btracker:
|
|
h_exit(&mq->hotspot_table);
|
|
bad_alloc_hotspot_table:
|
|
h_exit(&mq->table);
|
|
bad_alloc_table:
|
|
free_bitset(mq->cache_hit_bits);
|
|
bad_cache_hit_bits:
|
|
free_bitset(mq->hotspot_hit_bits);
|
|
bad_hotspot_hit_bits:
|
|
space_exit(&mq->es);
|
|
bad_pool_init:
|
|
kfree(mq);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct dm_cache_policy *smq_create(dm_cblock_t cache_size,
|
|
sector_t origin_size,
|
|
sector_t cache_block_size)
|
|
{
|
|
return __smq_create(cache_size, origin_size, cache_block_size, false, true);
|
|
}
|
|
|
|
static struct dm_cache_policy *mq_create(dm_cblock_t cache_size,
|
|
sector_t origin_size,
|
|
sector_t cache_block_size)
|
|
{
|
|
return __smq_create(cache_size, origin_size, cache_block_size, true, true);
|
|
}
|
|
|
|
static struct dm_cache_policy *cleaner_create(dm_cblock_t cache_size,
|
|
sector_t origin_size,
|
|
sector_t cache_block_size)
|
|
{
|
|
return __smq_create(cache_size, origin_size, cache_block_size, false, false);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static struct dm_cache_policy_type smq_policy_type = {
|
|
.name = "smq",
|
|
.version = {2, 0, 0},
|
|
.hint_size = 4,
|
|
.owner = THIS_MODULE,
|
|
.create = smq_create
|
|
};
|
|
|
|
static struct dm_cache_policy_type mq_policy_type = {
|
|
.name = "mq",
|
|
.version = {2, 0, 0},
|
|
.hint_size = 4,
|
|
.owner = THIS_MODULE,
|
|
.create = mq_create,
|
|
};
|
|
|
|
static struct dm_cache_policy_type cleaner_policy_type = {
|
|
.name = "cleaner",
|
|
.version = {2, 0, 0},
|
|
.hint_size = 4,
|
|
.owner = THIS_MODULE,
|
|
.create = cleaner_create,
|
|
};
|
|
|
|
static struct dm_cache_policy_type default_policy_type = {
|
|
.name = "default",
|
|
.version = {2, 0, 0},
|
|
.hint_size = 4,
|
|
.owner = THIS_MODULE,
|
|
.create = smq_create,
|
|
.real = &smq_policy_type
|
|
};
|
|
|
|
static int __init smq_init(void)
|
|
{
|
|
int r;
|
|
|
|
r = dm_cache_policy_register(&smq_policy_type);
|
|
if (r) {
|
|
DMERR("register failed %d", r);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
r = dm_cache_policy_register(&mq_policy_type);
|
|
if (r) {
|
|
DMERR("register failed (as mq) %d", r);
|
|
goto out_mq;
|
|
}
|
|
|
|
r = dm_cache_policy_register(&cleaner_policy_type);
|
|
if (r) {
|
|
DMERR("register failed (as cleaner) %d", r);
|
|
goto out_cleaner;
|
|
}
|
|
|
|
r = dm_cache_policy_register(&default_policy_type);
|
|
if (r) {
|
|
DMERR("register failed (as default) %d", r);
|
|
goto out_default;
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_default:
|
|
dm_cache_policy_unregister(&cleaner_policy_type);
|
|
out_cleaner:
|
|
dm_cache_policy_unregister(&mq_policy_type);
|
|
out_mq:
|
|
dm_cache_policy_unregister(&smq_policy_type);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static void __exit smq_exit(void)
|
|
{
|
|
dm_cache_policy_unregister(&cleaner_policy_type);
|
|
dm_cache_policy_unregister(&smq_policy_type);
|
|
dm_cache_policy_unregister(&mq_policy_type);
|
|
dm_cache_policy_unregister(&default_policy_type);
|
|
}
|
|
|
|
module_init(smq_init);
|
|
module_exit(smq_exit);
|
|
|
|
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_DESCRIPTION("smq cache policy");
|
|
|
|
MODULE_ALIAS("dm-cache-default");
|
|
MODULE_ALIAS("dm-cache-mq");
|
|
MODULE_ALIAS("dm-cache-cleaner");
|