On Fri, 12 Feb 2010 10:07:25 +0200
"Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
> On Fri, Feb 12, 2010 at 8:48 AM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> > Memcg has 2 eventcountes which counts "the same" event. Just usages are
> > different from each other. This patch tries to reduce event counter.
> >
> > This patch's logic uses "only increment, no reset" new_counter and masks for each
> > checks. Softlimit chesk was done per 1000 events. So, the similar check
> > can be done by !(new_counter & 0x3ff). Threshold check was done per 100
> > events. So, the similar check can be done by (!new_counter & 0x7f)
>
> IIUC, with this change we have to check counter after each update,
> since we check
> for exact value.
Yes.
> So we have to move checks to mem_cgroup_charge_statistics() or
> call them after each statistics charging. I'm not sure how it affects
> performance.
>
My patch 1/2 does it.
But hmm, move-task does counter updates in asynchronous manner. Then, there are
bug. I'll add check in the next version.
Maybe calling update_tree and threshold_check at the end of mova_task is
better. Does thresholds user take care of batched-move manner in task_move ?
Should we check one by one ?
(Maybe there will be another trouble when we handle hugepages...)
Thanks,
-Kame
> > Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> > Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
> > Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > ---
> > mm/memcontrol.c | 36 ++++++++++++------------------------
> > 1 file changed, 12 insertions(+), 24 deletions(-)
> >
> > Index: mmotm-2.6.33-Feb10/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-2.6.33-Feb10.orig/mm/memcontrol.c
> > +++ mmotm-2.6.33-Feb10/mm/memcontrol.c
> > @@ -63,8 +63,8 @@ static int really_do_swap_account __init
> > #define do_swap_account (0)
> > #endif
> >
> > -#define SOFTLIMIT_EVENTS_THRESH (1000)
> > -#define THRESHOLDS_EVENTS_THRESH (100)
> > +#define SOFTLIMIT_EVENTS_THRESH (0x3ff) /* once in 1024 */
> > +#define THRESHOLDS_EVENTS_THRESH (0x7f) /* once in 128 */
> >
> > /*
> > * Statistics for memory cgroup.
> > @@ -79,10 +79,7 @@ enum mem_cgroup_stat_index {
> > MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */
> > MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */
> > MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
> > - MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out.
> > - used by soft limit implementation */
> > - MEM_CGROUP_STAT_THRESHOLDS, /* decrements on each page in/out.
> > - used by threshold implementation */
> > + MEM_CGROUP_EVENTS, /* incremented by 1 at pagein/pageout */
> >
> > MEM_CGROUP_STAT_NSTATS,
> > };
> > @@ -394,16 +391,12 @@ mem_cgroup_remove_exceeded(struct mem_cg
> >
> > static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem)
> > {
> > - bool ret = false;
> > s64 val;
> >
> > - val = this_cpu_read(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT]);
> > - if (unlikely(val < 0)) {
> > - this_cpu_write(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT],
> > - SOFTLIMIT_EVENTS_THRESH);
> > - ret = true;
> > - }
> > - return ret;
> > + val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
> > + if (unlikely(!(val & SOFTLIMIT_EVENTS_THRESH)))
> > + return true;
> > + return false;
> > }
> >
> > static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
> > @@ -542,8 +535,7 @@ static void mem_cgroup_charge_statistics
> > __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
> > else
> > __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
> > - __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT]);
> > - __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS]);
> > + __this_cpu_dec(mem->stat->count[MEM_CGROUP_EVENTS]);
> >
> > preempt_enable();
> > }
> > @@ -3211,16 +3203,12 @@ static int mem_cgroup_swappiness_write(s
> >
> > static bool mem_cgroup_threshold_check(struct mem_cgroup *mem)
> > {
> > - bool ret = false;
> > s64 val;
> >
> > - val = this_cpu_read(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS]);
> > - if (unlikely(val < 0)) {
> > - this_cpu_write(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS],
> > - THRESHOLDS_EVENTS_THRESH);
> > - ret = true;
> > - }
> > - return ret;
> > + val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
> > + if (unlikely(!(val & THRESHOLDS_EVENTS_THRESH)))
> > + return true;
> > + return false;
> > }
> >
> > static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
> >
> >
>
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