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authorKemi Wang <kemi.wang@intel.com>2017-11-16 04:38:22 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-16 05:21:07 +0300
commit4518085e127dff97e74f74a8780d7564e273bec8 (patch)
tree1ad9218a5ca77345ee644b62ff74639771414106
parent9a8ec03ed022b79e56dca820cf04debbb240c7b3 (diff)
downloadlinux-4518085e127dff97e74f74a8780d7564e273bec8.tar.xz
mm, sysctl: make NUMA stats configurable
This is the second step which introduces a tunable interface that allow numa stats configurable for optimizing zone_statistics(), as suggested by Dave Hansen and Ying Huang. ========================================================================= When page allocation performance becomes a bottleneck and you can tolerate some possible tool breakage and decreased numa counter precision, you can do: echo 0 > /proc/sys/vm/numa_stat In this case, numa counter update is ignored. We can see about *4.8%*(185->176) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench01 (single thread) and *8.1%*(343->315) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench03 (88 threads) running on a 2-Socket Broadwell-based server (88 threads, 126G memory). Benchmark link provided by Jesper D Brouer (increase loop times to 10000000): https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench ========================================================================= When page allocation performance is not a bottleneck and you want all tooling to work, you can do: echo 1 > /proc/sys/vm/numa_stat This is system default setting. Many thanks to Michal Hocko, Dave Hansen, Ying Huang and Vlastimil Babka for comments to help improve the original patch. [keescook@chromium.org: make sure mutex is a global static] Link: http://lkml.kernel.org/r/20171107213809.GA4314@beast Link: http://lkml.kernel.org/r/1508290927-8518-1-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang <kemi.wang@intel.com> Signed-off-by: Kees Cook <keescook@chromium.org> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Suggested-by: Dave Hansen <dave.hansen@intel.com> Suggested-by: Ying Huang <ying.huang@intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christopher Lameter <cl@linux.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/sysctl/vm.txt16
-rw-r--r--include/linux/vmstat.h10
-rw-r--r--kernel/sysctl.c9
-rw-r--r--mm/mempolicy.c3
-rw-r--r--mm/page_alloc.c6
-rw-r--r--mm/vmstat.c71
6 files changed, 115 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 3e579740b49f..055c8b3e1018 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -58,6 +58,7 @@ Currently, these files are in /proc/sys/vm:
- percpu_pagelist_fraction
- stat_interval
- stat_refresh
+- numa_stat
- swappiness
- user_reserve_kbytes
- vfs_cache_pressure
@@ -799,6 +800,21 @@ with no ill effects: errors and warnings on these stats are suppressed.)
==============================================================
+numa_stat
+
+This interface allows runtime configuration of numa statistics.
+
+When page allocation performance becomes a bottleneck and you can tolerate
+some possible tool breakage and decreased numa counter precision, you can
+do:
+ echo 0 > /proc/sys/vm/numa_stat
+
+When page allocation performance is not a bottleneck and you want all
+tooling to work, you can do:
+ echo 1 > /proc/sys/vm/numa_stat
+
+==============================================================
+
swappiness
This control is used to define how aggressive the kernel will swap
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 1e0cb72e0598..1779c9817b39 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -7,9 +7,19 @@
#include <linux/mmzone.h>
#include <linux/vm_event_item.h>
#include <linux/atomic.h>
+#include <linux/static_key.h>
extern int sysctl_stat_interval;
+#ifdef CONFIG_NUMA
+#define ENABLE_NUMA_STAT 1
+#define DISABLE_NUMA_STAT 0
+extern int sysctl_vm_numa_stat;
+DECLARE_STATIC_KEY_TRUE(vm_numa_stat_key);
+extern int sysctl_vm_numa_stat_handler(struct ctl_table *table,
+ int write, void __user *buffer, size_t *length, loff_t *ppos);
+#endif
+
#ifdef CONFIG_VM_EVENT_COUNTERS
/*
* Light weight per cpu counter implementation.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7638e2f7fff8..4a13a389e99b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1356,6 +1356,15 @@ static struct ctl_table vm_table[] = {
.mode = 0644,
.proc_handler = &hugetlb_mempolicy_sysctl_handler,
},
+ {
+ .procname = "numa_stat",
+ .data = &sysctl_vm_numa_stat,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sysctl_vm_numa_stat_handler,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
#endif
{
.procname = "hugetlb_shm_group",
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index dad166b736ba..4ce44d3ff03d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1915,6 +1915,9 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
struct page *page;
page = __alloc_pages(gfp, order, nid);
+ /* skip NUMA_INTERLEAVE_HIT counter update if numa stats is disabled */
+ if (!static_branch_likely(&vm_numa_stat_key))
+ return page;
if (page && page_to_nid(page) == nid) {
preempt_disable();
__inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7ca668e946e5..67f523c4711a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -82,6 +82,8 @@ DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
#endif
+DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
+
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
/*
* N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
@@ -2777,6 +2779,10 @@ static inline void zone_statistics(struct zone *preferred_zone, struct zone *z)
#ifdef CONFIG_NUMA
enum numa_stat_item local_stat = NUMA_LOCAL;
+ /* skip numa counters update if numa stats is disabled */
+ if (!static_branch_likely(&vm_numa_stat_key))
+ return;
+
if (z->node != numa_node_id())
local_stat = NUMA_OTHER;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 7d11554861e4..40b2db6db6b1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -32,6 +32,77 @@
#define NUMA_STATS_THRESHOLD (U16_MAX - 2)
+#ifdef CONFIG_NUMA
+int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
+
+/* zero numa counters within a zone */
+static void zero_zone_numa_counters(struct zone *zone)
+{
+ int item, cpu;
+
+ for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++) {
+ atomic_long_set(&zone->vm_numa_stat[item], 0);
+ for_each_online_cpu(cpu)
+ per_cpu_ptr(zone->pageset, cpu)->vm_numa_stat_diff[item]
+ = 0;
+ }
+}
+
+/* zero numa counters of all the populated zones */
+static void zero_zones_numa_counters(void)
+{
+ struct zone *zone;
+
+ for_each_populated_zone(zone)
+ zero_zone_numa_counters(zone);
+}
+
+/* zero global numa counters */
+static void zero_global_numa_counters(void)
+{
+ int item;
+
+ for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++)
+ atomic_long_set(&vm_numa_stat[item], 0);
+}
+
+static void invalid_numa_statistics(void)
+{
+ zero_zones_numa_counters();
+ zero_global_numa_counters();
+}
+
+static DEFINE_MUTEX(vm_numa_stat_lock);
+
+int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
+{
+ int ret, oldval;
+
+ mutex_lock(&vm_numa_stat_lock);
+ if (write)
+ oldval = sysctl_vm_numa_stat;
+ ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (ret || !write)
+ goto out;
+
+ if (oldval == sysctl_vm_numa_stat)
+ goto out;
+ else if (sysctl_vm_numa_stat == ENABLE_NUMA_STAT) {
+ static_branch_enable(&vm_numa_stat_key);
+ pr_info("enable numa statistics\n");
+ } else {
+ static_branch_disable(&vm_numa_stat_key);
+ invalid_numa_statistics();
+ pr_info("disable numa statistics, and clear numa counters\n");
+ }
+
+out:
+ mutex_unlock(&vm_numa_stat_lock);
+ return ret;
+}
+#endif
+
#ifdef CONFIG_VM_EVENT_COUNTERS
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
EXPORT_PER_CPU_SYMBOL(vm_event_states);