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Subject[PATCH 1/5] vmstat: Implement refresh_vm_stats()
Date
This function forcibly flushes per-cpu vmstat diff counters to the
global counters.

Note that we don't try to flush percpu pagesets, the pcp will be
still flushed once per 3 seconds.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
include/linux/vmstat.h | 2 ++
mm/vmstat.c | 22 +++++++++++++++++++++-
2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 65efb92..2a53896 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -200,6 +200,7 @@ extern void __inc_zone_state(struct zone *, enum zone_stat_item);
extern void dec_zone_state(struct zone *, enum zone_stat_item);
extern void __dec_zone_state(struct zone *, enum zone_stat_item);

+void refresh_vm_stats(void);
void refresh_cpu_vm_stats(int);
void refresh_zone_stat_thresholds(void);

@@ -253,6 +254,7 @@ static inline void __dec_zone_page_state(struct page *page,

#define set_pgdat_percpu_threshold(pgdat, callback) { }

+static inline void refresh_vm_stats(void) { }
static inline void refresh_cpu_vm_stats(int cpu) { }
static inline void refresh_zone_stat_thresholds(void) { }

diff --git a/mm/vmstat.c b/mm/vmstat.c
index f600557..4a9d432 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -13,6 +13,7 @@
#include <linux/err.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/vmstat.h>
#include <linux/sched.h>
@@ -434,7 +435,7 @@ EXPORT_SYMBOL(dec_zone_page_state);
* with the global counters. These could cause remote node cache line
* bouncing and will have to be only done when necessary.
*/
-void refresh_cpu_vm_stats(int cpu)
+static void __refresh_cpu_vm_stats(int cpu, bool drain_pcp)
{
struct zone *zone;
int i;
@@ -456,11 +457,15 @@ void refresh_cpu_vm_stats(int cpu)
local_irq_restore(flags);
atomic_long_add(v, &zone->vm_stat[i]);
global_diff[i] += v;
+ if (!drain_pcp)
+ continue;
#ifdef CONFIG_NUMA
/* 3 seconds idle till flush */
p->expire = 3;
#endif
}
+ if (!drain_pcp)
+ continue;
cond_resched();
#ifdef CONFIG_NUMA
/*
@@ -495,6 +500,21 @@ void refresh_cpu_vm_stats(int cpu)
atomic_long_add(global_diff[i], &vm_stat[i]);
}

+void refresh_cpu_vm_stats(int cpu)
+{
+ __refresh_cpu_vm_stats(cpu, 1);
+}
+
+static void smp_call_refresh_cpu_vm_stats(void *info)
+{
+ __refresh_cpu_vm_stats(smp_processor_id(), 0);
+}
+
+void refresh_vm_stats(void)
+{
+ smp_call_function(smp_call_refresh_cpu_vm_stats, NULL, 1);
+}
+
#endif

#ifdef CONFIG_NUMA
--
1.7.9.2


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