On Fri, Dec 28, 2012 at 9:45 AM, Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > (2012/12/26 2:27), Sha Zhengju wrote: >> From: Sha Zhengju <handai.szj@xxxxxxxxxx> >> >> It's inspired by a similar optimization from Glauber Costa >> (memcg: make it suck faster; https://lkml.org/lkml/2012/9/25/154). >> Here we use jump label to patch the memcg page stat accounting code >> in or out when not used. when the first non-root memcg comes to >> life the code is patching in otherwise it is out. >> >> Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx> >> --- >> include/linux/memcontrol.h | 9 +++++++++ >> mm/memcontrol.c | 8 ++++++++ >> 2 files changed, 17 insertions(+) >> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index 1d22b81..3c4430c 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h >> @@ -56,6 +56,9 @@ struct mem_cgroup_reclaim_cookie { >> }; >> >> #ifdef CONFIG_MEMCG >> + >> +extern struct static_key memcg_in_use_key; >> + >> /* >> * All "charge" functions with gfp_mask should use GFP_KERNEL or >> * (gfp_mask & GFP_RECLAIM_MASK). In current implementatin, memcg doesn't >> @@ -158,6 +161,9 @@ extern atomic_t memcg_moving; >> static inline void mem_cgroup_begin_update_page_stat(struct page *page, >> bool *locked, unsigned long *flags) >> { >> + if (!static_key_false(&memcg_in_use_key)) >> + return; >> + >> if (mem_cgroup_disabled()) >> return; >> rcu_read_lock(); >> @@ -171,6 +177,9 @@ void __mem_cgroup_end_update_page_stat(struct page *page, >> static inline void mem_cgroup_end_update_page_stat(struct page *page, >> bool *locked, unsigned long *flags) >> { >> + if (!static_key_false(&memcg_in_use_key)) >> + return; >> + >> if (mem_cgroup_disabled()) >> return; >> if (*locked) >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 0cb5187..a2f73d7 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -531,6 +531,8 @@ enum res_type { >> #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 >> #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) >> >> +struct static_key memcg_in_use_key; >> + >> static void mem_cgroup_get(struct mem_cgroup *memcg); >> static void mem_cgroup_put(struct mem_cgroup *memcg); >> >> @@ -2226,6 +2228,9 @@ void mem_cgroup_update_page_stat(struct page *page, >> struct page_cgroup *pc = lookup_page_cgroup(page); >> unsigned long uninitialized_var(flags); >> >> + if (!static_key_false(&memcg_in_use_key)) >> + return; >> + >> if (mem_cgroup_disabled()) >> return; >> >> @@ -6340,6 +6345,8 @@ mem_cgroup_css_alloc(struct cgroup *cont) >> parent = mem_cgroup_from_cont(cont->parent); >> memcg->use_hierarchy = parent->use_hierarchy; >> memcg->oom_kill_disable = parent->oom_kill_disable; >> + >> + static_key_slow_inc(&memcg_in_use_key); >> } >> >> if (parent && parent->use_hierarchy) { >> @@ -6407,6 +6414,7 @@ static void mem_cgroup_css_free(struct cgroup *cont) >> kmem_cgroup_destroy(memcg); >> >> memcg_dangling_add(memcg); >> + static_key_slow_dec(&memcg_in_use_key); > > Hmm. I think this part should be folded into disarm_static_keys(). > Yeah, now I think there is more suitable. Thanks, Sha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>