The patch titled
Subject: mm: consider the number in local CPUs when reading NUMA stats
has been added to the -mm tree. Its filename is
mm-consider-the-number-in-local-cpus-when-reads-numa-stats.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-consider-the-number-in-local-cpus-when-reads-numa-stats.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-consider-the-number-in-local-cpus-when-reads-numa-stats.patch
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------------------------------------------------------
From: Kemi Wang <kemi.wang@xxxxxxxxx>
Subject: mm: consider the number in local CPUs when reading NUMA stats
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@xxxxxxxxx
Signed-off-by: Kemi Wang <kemi.wang@xxxxxxxxx>
Reported-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Aaron Lu <aaron.lu@xxxxxxxxx>
Cc: Andi Kleen <andi.kleen@xxxxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Tim Chen <tim.c.chen@xxxxxxxxx>
Cc: Ying Huang <ying.huang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/vmstat.h | 6 +++++-
mm/vmstat.c | 9 +++++++--
2 files changed, 12 insertions(+), 3 deletions(-)
diff -puN include/linux/vmstat.h~mm-consider-the-number-in-local-cpus-when-reads-numa-stats include/linux/vmstat.h
--- a/include/linux/vmstat.h~mm-consider-the-number-in-local-cpus-when-reads-numa-stats
+++ a/include/linux/vmstat.h
@@ -125,10 +125,14 @@ static inline unsigned long global_numa_
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;
}
diff -puN mm/vmstat.c~mm-consider-the-number-in-local-cpus-when-reads-numa-stats mm/vmstat.c
--- a/mm/vmstat.c~mm-consider-the-number-in-local-cpus-when-reads-numa-stats
+++ a/mm/vmstat.c
@@ -895,6 +895,10 @@ unsigned long sum_zone_node_page_state(i
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)
{
@@ -903,7 +907,7 @@ unsigned long sum_zone_numa_state(int no
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;
}
@@ -1534,7 +1538,7 @@ static void zoneinfo_show_print(struct s
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");
@@ -1790,6 +1794,7 @@ 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.
_
Patches currently in -mm which might be from kemi.wang@xxxxxxxxx are
mm-change-the-call-sites-of-numa-statistics-items.patch
mm-update-numa-counter-threshold-size.patch
mm-consider-the-number-in-local-cpus-when-reads-numa-stats.patch
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