Messages in this thread Patch in this message | | | From | Kemi Wang <> | Subject | [PATCH v2 3/3] mm: Consider the number in local CPUs when *reads* NUMA stats | Date | Thu, 24 Aug 2017 18:00:01 +0800 |
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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.
Changelog: v2: a) new creation.
Signed-off-by: Kemi Wang <kemi.wang@intel.com> --- include/linux/vmstat.h | 6 +++++- mm/vmstat.c | 9 +++++++-- 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index a29bd98..72e9ca6 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -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; } diff --git a/mm/vmstat.c b/mm/vmstat.c index b015f39..abeab81 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -895,6 +895,10 @@ 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) { @@ -903,7 +907,7 @@ 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; } @@ -1534,7 +1538,7 @@ 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"); @@ -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. -- 2.7.4
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