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authorChristoph Lameter <cl@linux.com>2016-01-15 02:21:40 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-15 03:00:49 +0300
commit0eb77e9880321915322d42913c3b53241739c8aa (patch)
tree5beff1411a4178b6157b78fcd6ef7302050f2641 /mm/vmstat.c
parent686739f6af5e8d5687ffebbf1193ff066aada6d9 (diff)
downloadlinux-0eb77e9880321915322d42913c3b53241739c8aa.tar.xz
vmstat: make vmstat_updater deferrable again and shut down on idle
Currently the vmstat updater is not deferrable as a result of commit ba4877b9ca51 ("vmstat: do not use deferrable delayed work for vmstat_update"). This in turn can cause multiple interruptions of the applications because the vmstat updater may run at Make vmstate_update deferrable again and provide a function that folds the differentials when the processor is going to idle mode thus addressing the issue of the above commit in a clean way. Note that the shepherd thread will continue scanning the differentials from another processor and will reenable the vmstat workers if it detects any changes. Fixes: ba4877b9ca51 ("vmstat: do not use deferrable delayed work for vmstat_update") Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
-rw-r--r--mm/vmstat.c69
1 files changed, 44 insertions, 25 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index c54fd2924f25..83a003bc3cae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -460,7 +460,7 @@ static int fold_diff(int *diff)
*
* The function returns the number of global counters updated.
*/
-static int refresh_cpu_vm_stats(void)
+static int refresh_cpu_vm_stats(bool do_pagesets)
{
struct zone *zone;
int i;
@@ -484,33 +484,35 @@ static int refresh_cpu_vm_stats(void)
#endif
}
}
- cond_resched();
#ifdef CONFIG_NUMA
- /*
- * Deal with draining the remote pageset of this
- * processor
- *
- * Check if there are pages remaining in this pageset
- * if not then there is nothing to expire.
- */
- if (!__this_cpu_read(p->expire) ||
+ if (do_pagesets) {
+ cond_resched();
+ /*
+ * Deal with draining the remote pageset of this
+ * processor
+ *
+ * Check if there are pages remaining in this pageset
+ * if not then there is nothing to expire.
+ */
+ if (!__this_cpu_read(p->expire) ||
!__this_cpu_read(p->pcp.count))
- continue;
+ continue;
- /*
- * We never drain zones local to this processor.
- */
- if (zone_to_nid(zone) == numa_node_id()) {
- __this_cpu_write(p->expire, 0);
- continue;
- }
+ /*
+ * We never drain zones local to this processor.
+ */
+ if (zone_to_nid(zone) == numa_node_id()) {
+ __this_cpu_write(p->expire, 0);
+ continue;
+ }
- if (__this_cpu_dec_return(p->expire))
- continue;
+ if (__this_cpu_dec_return(p->expire))
+ continue;
- if (__this_cpu_read(p->pcp.count)) {
- drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
- changes++;
+ if (__this_cpu_read(p->pcp.count)) {
+ drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
+ changes++;
+ }
}
#endif
}
@@ -1386,7 +1388,7 @@ static cpumask_var_t cpu_stat_off;
static void vmstat_update(struct work_struct *w)
{
- if (refresh_cpu_vm_stats()) {
+ if (refresh_cpu_vm_stats(true)) {
/*
* Counters were updated so we expect more updates
* to occur in the future. Keep on running the
@@ -1418,6 +1420,23 @@ static void vmstat_update(struct work_struct *w)
}
/*
+ * Switch off vmstat processing and then fold all the remaining differentials
+ * until the diffs stay at zero. The function is used by NOHZ and can only be
+ * invoked when tick processing is not active.
+ */
+void quiet_vmstat(void)
+{
+ if (system_state != SYSTEM_RUNNING)
+ return;
+
+ do {
+ if (!cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off))
+ cancel_delayed_work(this_cpu_ptr(&vmstat_work));
+
+ } while (refresh_cpu_vm_stats(false));
+}
+
+/*
* Check if the diffs for a certain cpu indicate that
* an update is needed.
*/
@@ -1449,7 +1468,7 @@ static bool need_update(int cpu)
*/
static void vmstat_shepherd(struct work_struct *w);
-static DECLARE_DELAYED_WORK(shepherd, vmstat_shepherd);
+static DECLARE_DEFERRABLE_WORK(shepherd, vmstat_shepherd);
static void vmstat_shepherd(struct work_struct *w)
{