On Fri, Feb 12, 2010 at 11:09 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.
>
> Now logic uses "only increment, no reset" counter and masks for each
> checks. Softlimit chesk was done per 1000 evetns. 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)
>
> ALL event checks are done right after EVENT percpu counter is updated.
>
> Changelog: 2010/02/12
> - fixed to use "inc" rather than "dec"
> - modified to be more unified style of counter handling.
> - taking care of account-move.
>
> 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 | 86 ++++++++++++++++++++++++++------------------------------
> 1 file changed, 41 insertions(+), 45 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 +63,15 @@ static int really_do_swap_account __init
> #define do_swap_account (0)
> #endif
>
> -#define SOFTLIMIT_EVENTS_THRESH (1000)
> -#define THRESHOLDS_EVENTS_THRESH (100)
> +/*
> + * Per memcg event counter is incremented at every pagein/pageout. This counter
> + * is used for trigger some periodic events. This is straightforward and better
> + * than using jiffies etc. to handle periodic memcg event.
> + *
> + * These values will be used as !((event) & ((1 <<(thresh)) - 1))
> + */
> +#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
> +#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
>
> /*
> * Statistics for memory cgroup.
> @@ -79,10 +86,7 @@ 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 at every pagein/pageout */
>
> MEM_CGROUP_STAT_NSTATS,
> };
> @@ -154,7 +158,6 @@ struct mem_cgroup_threshold_ary {
> struct mem_cgroup_threshold entries[0];
> };
>
> -static bool mem_cgroup_threshold_check(struct mem_cgroup *mem);
> static void mem_cgroup_threshold(struct mem_cgroup *mem);
>
> /*
> @@ -392,19 +395,6 @@ mem_cgroup_remove_exceeded(struct mem_cg
> spin_unlock(&mctz->lock);
> }
>
> -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;
> -}
>
> static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
> {
> @@ -542,8 +532,7 @@ 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_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
>
> preempt_enable();
> }
> @@ -563,6 +552,29 @@ static unsigned long mem_cgroup_get_loca
> return total;
> }
>
> +static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
inline?
> +{
> + s64 val;
> +
> + val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
> +
> + return !(val & ((1 << event_mask_shift) - 1));
> +}
> +
> +/*
> + * Check events in order.
> + *
> + */
> +static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
Ditto.
> +{
> + /* threshold event is triggered in finer grain than soft limit */
> + if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
> + mem_cgroup_threshold(mem);
> + if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
> + mem_cgroup_update_tree(mem, page);
> + }
> +}
> +
> static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> {
> return container_of(cgroup_subsys_state(cont,
> @@ -1686,11 +1698,7 @@ static void __mem_cgroup_commit_charge(s
> * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
> * if they exceeds softlimit.
> */
> - if (mem_cgroup_soft_limit_check(mem))
> - mem_cgroup_update_tree(mem, pc->page);
> - if (mem_cgroup_threshold_check(mem))
> - mem_cgroup_threshold(mem);
> -
> + memcg_check_events(mem, pc->page);
> }
>
> /**
> @@ -1760,6 +1768,11 @@ static int mem_cgroup_move_account(struc
> ret = 0;
> }
> unlock_page_cgroup(pc);
> + /*
> + * check events
> + */
> + memcg_check_events(to, pc->page);
> + memcg_check_events(from, pc->page);
> return ret;
> }
>
> @@ -2128,10 +2141,7 @@ __mem_cgroup_uncharge_common(struct page
> mz = page_cgroup_zoneinfo(pc);
> unlock_page_cgroup(pc);
>
> - if (mem_cgroup_soft_limit_check(mem))
> - mem_cgroup_update_tree(mem, page);
> - if (mem_cgroup_threshold_check(mem))
> - mem_cgroup_threshold(mem);
> + memcg_check_events(mem, page);
> /* at swapout, this memcg will be accessed to record to swap */
> if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
> css_put(&mem->css);
> @@ -3207,20 +3217,6 @@ static int mem_cgroup_swappiness_write(s
> return 0;
> }
>
> -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;
> -}
> -
> static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
> {
> struct mem_cgroup_threshold_ary *t;
>
>
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