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![Vasily Gorbik](/assets/img/avatar_default.png)
When command line options are used without specifying values (e.g. "emu_size" instead of "emu_size="), the value is NULL. Check that before performing string operations and further processing. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
577 lines
14 KiB
C
577 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* NUMA support for s390
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*
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* NUMA emulation (aka fake NUMA) distributes the available memory to nodes
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* without using real topology information about the physical memory of the
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* machine.
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*
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* It distributes the available CPUs to nodes while respecting the original
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* machine topology information. This is done by trying to avoid to separate
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* CPUs which reside on the same book or even on the same MC.
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*
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* Because the current Linux scheduler code requires a stable cpu to node
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* mapping, cores are pinned to nodes when the first CPU thread is set online.
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*
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* Copyright IBM Corp. 2015
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*/
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#define KMSG_COMPONENT "numa_emu"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/kernel.h>
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#include <linux/cpumask.h>
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#include <linux/memblock.h>
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#include <linux/node.h>
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#include <linux/memory.h>
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#include <linux/slab.h>
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#include <asm/smp.h>
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#include <asm/topology.h>
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#include "numa_mode.h"
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#include "toptree.h"
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/* Distances between the different system components */
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#define DIST_EMPTY 0
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#define DIST_CORE 1
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#define DIST_MC 2
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#define DIST_BOOK 3
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#define DIST_DRAWER 4
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#define DIST_MAX 5
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/* Node distance reported to common code */
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#define EMU_NODE_DIST 10
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/* Node ID for free (not yet pinned) cores */
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#define NODE_ID_FREE -1
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/* Different levels of toptree */
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enum toptree_level {CORE, MC, BOOK, DRAWER, NODE, TOPOLOGY};
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/* The two toptree IDs */
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enum {TOPTREE_ID_PHYS, TOPTREE_ID_NUMA};
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/* Number of NUMA nodes */
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static int emu_nodes = 1;
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/* NUMA stripe size */
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static unsigned long emu_size;
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/*
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* Node to core pinning information updates are protected by
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* "sched_domains_mutex".
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*/
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static struct {
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s32 to_node_id[CONFIG_NR_CPUS]; /* Pinned core to node mapping */
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int total; /* Total number of pinned cores */
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int per_node_target; /* Cores per node without extra cores */
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int per_node[MAX_NUMNODES]; /* Number of cores pinned to node */
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} *emu_cores;
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/*
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* Pin a core to a node
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*/
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static void pin_core_to_node(int core_id, int node_id)
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{
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if (emu_cores->to_node_id[core_id] == NODE_ID_FREE) {
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emu_cores->per_node[node_id]++;
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emu_cores->to_node_id[core_id] = node_id;
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emu_cores->total++;
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} else {
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WARN_ON(emu_cores->to_node_id[core_id] != node_id);
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}
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}
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/*
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* Number of pinned cores of a node
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*/
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static int cores_pinned(struct toptree *node)
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{
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return emu_cores->per_node[node->id];
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}
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/*
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* ID of the node where the core is pinned (or NODE_ID_FREE)
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*/
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static int core_pinned_to_node_id(struct toptree *core)
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{
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return emu_cores->to_node_id[core->id];
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}
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/*
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* Number of cores in the tree that are not yet pinned
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*/
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static int cores_free(struct toptree *tree)
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{
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struct toptree *core;
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int count = 0;
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toptree_for_each(core, tree, CORE) {
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if (core_pinned_to_node_id(core) == NODE_ID_FREE)
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count++;
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}
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return count;
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}
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/*
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* Return node of core
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*/
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static struct toptree *core_node(struct toptree *core)
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{
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return core->parent->parent->parent->parent;
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}
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/*
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* Return drawer of core
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*/
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static struct toptree *core_drawer(struct toptree *core)
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{
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return core->parent->parent->parent;
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}
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/*
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* Return book of core
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*/
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static struct toptree *core_book(struct toptree *core)
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{
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return core->parent->parent;
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}
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/*
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* Return mc of core
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*/
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static struct toptree *core_mc(struct toptree *core)
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{
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return core->parent;
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}
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/*
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* Distance between two cores
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*/
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static int dist_core_to_core(struct toptree *core1, struct toptree *core2)
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{
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if (core_drawer(core1)->id != core_drawer(core2)->id)
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return DIST_DRAWER;
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if (core_book(core1)->id != core_book(core2)->id)
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return DIST_BOOK;
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if (core_mc(core1)->id != core_mc(core2)->id)
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return DIST_MC;
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/* Same core or sibling on same MC */
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return DIST_CORE;
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}
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/*
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* Distance of a node to a core
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*/
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static int dist_node_to_core(struct toptree *node, struct toptree *core)
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{
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struct toptree *core_node;
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int dist_min = DIST_MAX;
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toptree_for_each(core_node, node, CORE)
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dist_min = min(dist_min, dist_core_to_core(core_node, core));
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return dist_min == DIST_MAX ? DIST_EMPTY : dist_min;
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}
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/*
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* Unify will delete empty nodes, therefore recreate nodes.
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*/
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static void toptree_unify_tree(struct toptree *tree)
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{
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int nid;
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toptree_unify(tree);
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for (nid = 0; nid < emu_nodes; nid++)
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toptree_get_child(tree, nid);
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}
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/*
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* Find the best/nearest node for a given core and ensure that no node
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* gets more than "emu_cores->per_node_target + extra" cores.
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*/
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static struct toptree *node_for_core(struct toptree *numa, struct toptree *core,
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int extra)
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{
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struct toptree *node, *node_best = NULL;
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int dist_cur, dist_best, cores_target;
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cores_target = emu_cores->per_node_target + extra;
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dist_best = DIST_MAX;
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node_best = NULL;
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toptree_for_each(node, numa, NODE) {
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/* Already pinned cores must use their nodes */
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if (core_pinned_to_node_id(core) == node->id) {
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node_best = node;
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break;
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}
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/* Skip nodes that already have enough cores */
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if (cores_pinned(node) >= cores_target)
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continue;
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dist_cur = dist_node_to_core(node, core);
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if (dist_cur < dist_best) {
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dist_best = dist_cur;
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node_best = node;
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}
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}
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return node_best;
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}
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/*
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* Find the best node for each core with respect to "extra" core count
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*/
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static void toptree_to_numa_single(struct toptree *numa, struct toptree *phys,
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int extra)
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{
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struct toptree *node, *core, *tmp;
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toptree_for_each_safe(core, tmp, phys, CORE) {
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node = node_for_core(numa, core, extra);
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if (!node)
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return;
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toptree_move(core, node);
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pin_core_to_node(core->id, node->id);
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}
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}
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/*
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* Move structures of given level to specified NUMA node
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*/
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static void move_level_to_numa_node(struct toptree *node, struct toptree *phys,
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enum toptree_level level, bool perfect)
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{
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int cores_free, cores_target = emu_cores->per_node_target;
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struct toptree *cur, *tmp;
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toptree_for_each_safe(cur, tmp, phys, level) {
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cores_free = cores_target - toptree_count(node, CORE);
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if (perfect) {
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if (cores_free == toptree_count(cur, CORE))
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toptree_move(cur, node);
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} else {
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if (cores_free >= toptree_count(cur, CORE))
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toptree_move(cur, node);
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}
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}
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}
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/*
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* Move structures of a given level to NUMA nodes. If "perfect" is specified
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* move only perfectly fitting structures. Otherwise move also smaller
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* than needed structures.
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*/
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static void move_level_to_numa(struct toptree *numa, struct toptree *phys,
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enum toptree_level level, bool perfect)
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{
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struct toptree *node;
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toptree_for_each(node, numa, NODE)
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move_level_to_numa_node(node, phys, level, perfect);
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}
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/*
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* For the first run try to move the big structures
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*/
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static void toptree_to_numa_first(struct toptree *numa, struct toptree *phys)
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{
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struct toptree *core;
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/* Always try to move perfectly fitting structures first */
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move_level_to_numa(numa, phys, DRAWER, true);
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move_level_to_numa(numa, phys, DRAWER, false);
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move_level_to_numa(numa, phys, BOOK, true);
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move_level_to_numa(numa, phys, BOOK, false);
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move_level_to_numa(numa, phys, MC, true);
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move_level_to_numa(numa, phys, MC, false);
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/* Now pin all the moved cores */
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toptree_for_each(core, numa, CORE)
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pin_core_to_node(core->id, core_node(core)->id);
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}
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/*
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* Allocate new topology and create required nodes
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*/
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static struct toptree *toptree_new(int id, int nodes)
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{
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struct toptree *tree;
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int nid;
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tree = toptree_alloc(TOPOLOGY, id);
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if (!tree)
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goto fail;
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for (nid = 0; nid < nodes; nid++) {
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if (!toptree_get_child(tree, nid))
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goto fail;
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}
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return tree;
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fail:
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panic("NUMA emulation could not allocate topology");
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}
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/*
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* Allocate and initialize core to node mapping
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*/
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static void __ref create_core_to_node_map(void)
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{
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int i;
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emu_cores = memblock_alloc(sizeof(*emu_cores), 8);
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if (!emu_cores)
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panic("%s: Failed to allocate %zu bytes align=0x%x\n",
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__func__, sizeof(*emu_cores), 8);
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for (i = 0; i < ARRAY_SIZE(emu_cores->to_node_id); i++)
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emu_cores->to_node_id[i] = NODE_ID_FREE;
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}
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/*
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* Move cores from physical topology into NUMA target topology
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* and try to keep as much of the physical topology as possible.
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*/
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static struct toptree *toptree_to_numa(struct toptree *phys)
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{
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static int first = 1;
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struct toptree *numa;
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int cores_total;
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cores_total = emu_cores->total + cores_free(phys);
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emu_cores->per_node_target = cores_total / emu_nodes;
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numa = toptree_new(TOPTREE_ID_NUMA, emu_nodes);
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if (first) {
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toptree_to_numa_first(numa, phys);
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first = 0;
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}
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toptree_to_numa_single(numa, phys, 0);
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toptree_to_numa_single(numa, phys, 1);
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toptree_unify_tree(numa);
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WARN_ON(cpumask_weight(&phys->mask));
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return numa;
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}
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/*
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* Create a toptree out of the physical topology that we got from the hypervisor
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*/
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static struct toptree *toptree_from_topology(void)
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{
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struct toptree *phys, *node, *drawer, *book, *mc, *core;
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struct cpu_topology_s390 *top;
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int cpu;
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phys = toptree_new(TOPTREE_ID_PHYS, 1);
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for_each_cpu(cpu, &cpus_with_topology) {
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top = &cpu_topology[cpu];
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node = toptree_get_child(phys, 0);
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drawer = toptree_get_child(node, top->drawer_id);
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book = toptree_get_child(drawer, top->book_id);
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mc = toptree_get_child(book, top->socket_id);
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core = toptree_get_child(mc, smp_get_base_cpu(cpu));
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if (!drawer || !book || !mc || !core)
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panic("NUMA emulation could not allocate memory");
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cpumask_set_cpu(cpu, &core->mask);
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toptree_update_mask(mc);
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}
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return phys;
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}
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/*
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* Add toptree core to topology and create correct CPU masks
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*/
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static void topology_add_core(struct toptree *core)
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{
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struct cpu_topology_s390 *top;
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int cpu;
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for_each_cpu(cpu, &core->mask) {
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top = &cpu_topology[cpu];
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cpumask_copy(&top->thread_mask, &core->mask);
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cpumask_copy(&top->core_mask, &core_mc(core)->mask);
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cpumask_copy(&top->book_mask, &core_book(core)->mask);
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cpumask_copy(&top->drawer_mask, &core_drawer(core)->mask);
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cpumask_set_cpu(cpu, &node_to_cpumask_map[core_node(core)->id]);
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top->node_id = core_node(core)->id;
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}
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}
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/*
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* Apply toptree to topology and create CPU masks
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*/
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static void toptree_to_topology(struct toptree *numa)
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{
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struct toptree *core;
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int i;
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/* Clear all node masks */
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for (i = 0; i < MAX_NUMNODES; i++)
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cpumask_clear(&node_to_cpumask_map[i]);
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/* Rebuild all masks */
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toptree_for_each(core, numa, CORE)
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topology_add_core(core);
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}
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/*
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* Show the node to core mapping
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*/
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static void print_node_to_core_map(void)
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{
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int nid, cid;
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if (!numa_debug_enabled)
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return;
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printk(KERN_DEBUG "NUMA node to core mapping\n");
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for (nid = 0; nid < emu_nodes; nid++) {
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printk(KERN_DEBUG " node %3d: ", nid);
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for (cid = 0; cid < ARRAY_SIZE(emu_cores->to_node_id); cid++) {
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if (emu_cores->to_node_id[cid] == nid)
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printk(KERN_CONT "%d ", cid);
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}
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printk(KERN_CONT "\n");
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}
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}
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static void pin_all_possible_cpus(void)
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{
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int core_id, node_id, cpu;
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static int initialized;
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if (initialized)
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return;
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print_node_to_core_map();
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node_id = 0;
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for_each_possible_cpu(cpu) {
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core_id = smp_get_base_cpu(cpu);
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if (emu_cores->to_node_id[core_id] != NODE_ID_FREE)
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continue;
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pin_core_to_node(core_id, node_id);
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cpu_topology[cpu].node_id = node_id;
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node_id = (node_id + 1) % emu_nodes;
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}
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print_node_to_core_map();
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initialized = 1;
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}
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/*
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* Transfer physical topology into a NUMA topology and modify CPU masks
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* according to the NUMA topology.
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*
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* Must be called with "sched_domains_mutex" lock held.
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*/
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static void emu_update_cpu_topology(void)
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{
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struct toptree *phys, *numa;
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if (emu_cores == NULL)
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create_core_to_node_map();
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phys = toptree_from_topology();
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numa = toptree_to_numa(phys);
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toptree_free(phys);
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toptree_to_topology(numa);
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toptree_free(numa);
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pin_all_possible_cpus();
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}
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/*
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* If emu_size is not set, use CONFIG_EMU_SIZE. Then round to minimum
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* alignment (needed for memory hotplug).
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*/
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static unsigned long emu_setup_size_adjust(unsigned long size)
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{
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unsigned long size_new;
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size = size ? : CONFIG_EMU_SIZE;
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size_new = roundup(size, memory_block_size_bytes());
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if (size_new == size)
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return size;
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pr_warn("Increasing memory stripe size from %ld MB to %ld MB\n",
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size >> 20, size_new >> 20);
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return size_new;
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}
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/*
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* If we have not enough memory for the specified nodes, reduce the node count.
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*/
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static int emu_setup_nodes_adjust(int nodes)
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{
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int nodes_max;
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nodes_max = memblock.memory.total_size / emu_size;
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nodes_max = max(nodes_max, 1);
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if (nodes_max >= nodes)
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return nodes;
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pr_warn("Not enough memory for %d nodes, reducing node count\n", nodes);
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return nodes_max;
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}
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/*
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* Early emu setup
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*/
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static void emu_setup(void)
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{
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int nid;
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emu_size = emu_setup_size_adjust(emu_size);
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emu_nodes = emu_setup_nodes_adjust(emu_nodes);
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for (nid = 0; nid < emu_nodes; nid++)
|
|
node_set(nid, node_possible_map);
|
|
pr_info("Creating %d nodes with memory stripe size %ld MB\n",
|
|
emu_nodes, emu_size >> 20);
|
|
}
|
|
|
|
/*
|
|
* Return node id for given page number
|
|
*/
|
|
static int emu_pfn_to_nid(unsigned long pfn)
|
|
{
|
|
return (pfn / (emu_size >> PAGE_SHIFT)) % emu_nodes;
|
|
}
|
|
|
|
/*
|
|
* Return stripe size
|
|
*/
|
|
static unsigned long emu_align(void)
|
|
{
|
|
return emu_size;
|
|
}
|
|
|
|
/*
|
|
* Return distance between two nodes
|
|
*/
|
|
static int emu_distance(int node1, int node2)
|
|
{
|
|
return (node1 != node2) * EMU_NODE_DIST;
|
|
}
|
|
|
|
/*
|
|
* Define callbacks for generic s390 NUMA infrastructure
|
|
*/
|
|
const struct numa_mode numa_mode_emu = {
|
|
.name = "emu",
|
|
.setup = emu_setup,
|
|
.update_cpu_topology = emu_update_cpu_topology,
|
|
.__pfn_to_nid = emu_pfn_to_nid,
|
|
.align = emu_align,
|
|
.distance = emu_distance,
|
|
};
|
|
|
|
/*
|
|
* Kernel parameter: emu_nodes=<n>
|
|
*/
|
|
static int __init early_parse_emu_nodes(char *p)
|
|
{
|
|
int count;
|
|
|
|
if (!p || kstrtoint(p, 0, &count) != 0 || count <= 0)
|
|
return 0;
|
|
emu_nodes = min(count, MAX_NUMNODES);
|
|
return 0;
|
|
}
|
|
early_param("emu_nodes", early_parse_emu_nodes);
|
|
|
|
/*
|
|
* Kernel parameter: emu_size=[<n>[k|M|G|T]]
|
|
*/
|
|
static int __init early_parse_emu_size(char *p)
|
|
{
|
|
if (p)
|
|
emu_size = memparse(p, NULL);
|
|
return 0;
|
|
}
|
|
early_param("emu_size", early_parse_emu_size);
|