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. 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.
> 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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