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mm: multi-gen LRU: thrashing prevention 

Add /sys/kernel/mm/lru_gen/min_ttl_ms for thrashing prevention, as
requested by many desktop users [1].

When set to value N, it prevents the working set of N milliseconds from
getting evicted.  The OOM killer is triggered if this working set cannot
be kept in memory.  Based on the average human detectable lag (~100ms),
N=1000 usually eliminates intolerable lags due to thrashing.  Larger
values like N=3000 make lags less noticeable at the risk of premature OOM
kills.

Compared with the size-based approach [2], this time-based approach
has the following advantages:

1. It is easier to configure because it is agnostic to applications
   and memory sizes.
2. It is more reliable because it is directly wired to the OOM killer.

[1] https://lore.kernel.org/r/Ydza%2FzXKY9ATRoh6@google.com/
[2] https://lore.kernel.org/r/20101028191523.GA14972@google.com/

Link: https://lkml.kernel.org/r/20220918080010.2920238-12-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Larabel <Michael@MichaelLarabel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yu Zhao 2022-09-18 02:00:08 -06:00 committed by Andrew Morton
parent 354ed59744
commit 1332a809d9
2 changed files with 73 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/mmzone.h
View File

@ -422,6 +422,8 @@ struct lru_gen_struct {
unsigned long max_seq;
/* the eviction increments the oldest generation numbers */
unsigned long min_seq[ANON_AND_FILE];
/* the birth time of each generation in jiffies */
unsigned long timestamps[MAX_NR_GENS];
/* the multi-gen LRU lists, lazily sorted on eviction */
struct list_head lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES];
/* the multi-gen LRU sizes, eventually consistent */

74
mm/vmscan.c
View File

@ -4293,6 +4293,7 @@ static void inc_max_seq(struct lruvec *lruvec, bool can_swap)
for (type = 0; type < ANON_AND_FILE; type++)
reset_ctrl_pos(lruvec, type, false);
WRITE_ONCE(lrugen->timestamps[next], jiffies);
/* make sure preceding modifications appear */
smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
@ -4422,7 +4423,7 @@ static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq, unsig
return false;
}
static void age_lruvec(struct lruvec *lruvec, struct scan_control *sc)
static bool age_lruvec(struct lruvec *lruvec, struct scan_control *sc, unsigned long min_ttl)
{
bool need_aging;
unsigned long nr_to_scan;
@ -4436,16 +4437,36 @@ static void age_lruvec(struct lruvec *lruvec, struct scan_control *sc)
mem_cgroup_calculate_protection(NULL, memcg);
if (mem_cgroup_below_min(memcg))
return;
return false;
need_aging = should_run_aging(lruvec, max_seq, min_seq, sc, swappiness, &nr_to_scan);
if (min_ttl) {
int gen = lru_gen_from_seq(min_seq[LRU_GEN_FILE]);
unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
if (time_is_after_jiffies(birth + min_ttl))
return false;
/* the size is likely too small to be helpful */
if (!nr_to_scan && sc->priority != DEF_PRIORITY)
return false;
}
if (need_aging)
try_to_inc_max_seq(lruvec, max_seq, sc, swappiness);
return true;
}
/* to protect the working set of the last N jiffies */
static unsigned long lru_gen_min_ttl __read_mostly;
static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
{
struct mem_cgroup *memcg;
bool success = false;
unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl);
VM_WARN_ON_ONCE(!current_is_kswapd());
@ -4468,12 +4489,32 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
do {
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
age_lruvec(lruvec, sc);
if (age_lruvec(lruvec, sc, min_ttl))
success = true;
cond_resched();
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
clear_mm_walk();
/* check the order to exclude compaction-induced reclaim */
if (success || !min_ttl || sc->order)
return;
/*
* The main goal is to OOM kill if every generation from all memcgs is
* younger than min_ttl. However, another possibility is all memcgs are
* either below min or empty.
*/
if (mutex_trylock(&oom_lock)) {
struct oom_control oc = {
.gfp_mask = sc->gfp_mask,
};
out_of_memory(&oc);
mutex_unlock(&oom_lock);
}
}
/*
@ -5231,6 +5272,28 @@ unlock:
* sysfs interface
******************************************************************************/
static ssize_t show_min_ttl(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%u\n", jiffies_to_msecs(READ_ONCE(lru_gen_min_ttl)));
}
static ssize_t store_min_ttl(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t len)
{
unsigned int msecs;
if (kstrtouint(buf, 0, &msecs))
return -EINVAL;
WRITE_ONCE(lru_gen_min_ttl, msecs_to_jiffies(msecs));
return len;
}
static struct kobj_attribute lru_gen_min_ttl_attr = __ATTR(
min_ttl_ms, 0644, show_min_ttl, store_min_ttl
);
static ssize_t show_enabled(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
unsigned int caps = 0;
@ -5279,6 +5342,7 @@ static struct kobj_attribute lru_gen_enabled_attr = __ATTR(
);
static struct attribute *lru_gen_attrs[] = {
&lru_gen_min_ttl_attr.attr,
&lru_gen_enabled_attr.attr,
NULL
};
@ -5294,12 +5358,16 @@ static struct attribute_group lru_gen_attr_group = {
void lru_gen_init_lruvec(struct lruvec *lruvec)
{
int i;
int gen, type, zone;
struct lru_gen_struct *lrugen = &lruvec->lrugen;
lrugen->max_seq = MIN_NR_GENS + 1;
lrugen->enabled = lru_gen_enabled();
for (i = 0; i <= MIN_NR_GENS + 1; i++)
lrugen->timestamps[i] = jiffies;
for_each_gen_type_zone(gen, type, zone)
INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]);