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Commit 63803222 authored by Kemi Wang's avatar Kemi Wang Committed by Linus Torvalds
Browse files

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@intel.com


Signed-off-by: default avatarKemi Wang <kemi.wang@intel.com>
Reported-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: default avatarMel 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d90ca89

include/linux/vmstat.h

+5 −1
Original line number Diff line number Diff line
@@ -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;

}

mm/vmstat.c

+7 −2
Original line number Diff line number Diff line
@@ -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.