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mm: consider the number in local CPUs when reading NUMA stats

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To avoid deviation, the per cpu number of NUMA stats in
vm_numa_stat_diff[] is included when a user *reads* the NUMA stats.

Since NUMA stats does not be read by users frequently, and kernel does not
need it to make a decision, it will not be a problem to make the readers
more expensive.

Link: http://lkml.kernel.org/r/1503568801-21305-4-git-send-email-kemi.wang@intel.com
Signed-off-by: Kemi Wang <kemi.wang@intel.com>
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kemi Wang 2017-09-08 16:12:55 -07:00 committed by Linus Torvalds
parent 1d90ca897c
commit 638032224e
2 changed files with 12 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/vmstat.h
View file

@ -125,10 +125,14 @@ static inline unsigned long global_numa_state(enum numa_stat_item item)
return x;
}
static inline unsigned long zone_numa_state(struct zone *zone,
static inline unsigned long zone_numa_state_snapshot(struct zone *zone,
enum numa_stat_item item)
{
long x = atomic_long_read(&zone->vm_numa_stat[item]);
int cpu;
for_each_online_cpu(cpu)
x += per_cpu_ptr(zone->pageset, cpu)->vm_numa_stat_diff[item];
return x;
}

9
mm/vmstat.c
View file

@ -897,6 +897,10 @@ unsigned long sum_zone_node_page_state(int node,
return count;
}
/*
* Determine the per node value of a numa stat item. To avoid deviation,
* the per cpu stat number in vm_numa_stat_diff[] is also included.
*/
unsigned long sum_zone_numa_state(int node,
enum numa_stat_item item)
{
@ -905,7 +909,7 @@ unsigned long sum_zone_numa_state(int node,
unsigned long count = 0;
for (i = 0; i < MAX_NR_ZONES; i++)
count += zone_numa_state(zones + i, item);
count += zone_numa_state_snapshot(zones + i, item);
return count;
}
@ -1536,7 +1540,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
seq_printf(m, "\n %-12s %lu",
vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
zone_numa_state(zone, i));
zone_numa_state_snapshot(zone, i));
#endif
seq_printf(m, "\n pagesets");
@ -1792,6 +1796,7 @@ static bool need_update(int cpu)
#ifdef CONFIG_NUMA
BUILD_BUG_ON(sizeof(p->vm_numa_stat_diff[0]) != 2);
#endif
/*
* The fast way of checking if there are any vmstat diffs.
* This works because the diffs are byte sized items.