From 138870520aaa04ade8512520808de2befd5ae92d Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 26 Jun 2014 10:42:37 +1000 Subject: [PATCH] mm: memcontrol: use root_mem_cgroup res_counter Due to an old optimization to keep expensive res_counter changes at a minimum, the root_mem_cgroup res_counter is never charged; there is no limit at that level anyway, and any statistics can be generated on demand by summing up the counters of all other cgroups. However, with per-cpu charge caches, res_counter operations do not even show up in profiles anymore, so this optimization is no longer necessary. Remove it to simplify the code. Signed-off-by: Johannes Weiner Acked-by: Michal Hocko Cc: Hugh Dickins Cc: Tejun Heo Cc: Vladimir Davydov Signed-off-by: Andrew Morton --- mm/memcontrol.c | 152 ++++++++++++++---------------------------------- 1 file changed, 44 insertions(+), 108 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d1e450f605bc..dae8c2fdab83 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2570,9 +2570,8 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg, unsigned long nr_reclaimed; unsigned long flags = 0; unsigned long long size; + int ret = 0; - if (mem_cgroup_is_root(memcg)) - goto done; retry: if (consume_stock(memcg, nr_pages)) goto done; @@ -2650,13 +2649,15 @@ nomem: if (!(gfp_mask & __GFP_NOFAIL)) return -ENOMEM; bypass: - return -EINTR; + memcg = root_mem_cgroup; + ret = -EINTR; + goto retry; done_restock: if (batch > nr_pages) refill_stock(memcg, batch - nr_pages); done: - return 0; + return ret; } /** @@ -2695,13 +2696,11 @@ static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm, static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) { - if (!mem_cgroup_is_root(memcg)) { - unsigned long bytes = nr_pages * PAGE_SIZE; + unsigned long bytes = nr_pages * PAGE_SIZE; - res_counter_uncharge(&memcg->res, bytes); - if (do_swap_account) - res_counter_uncharge(&memcg->memsw, bytes); - } + res_counter_uncharge(&memcg->res, bytes); + if (do_swap_account) + res_counter_uncharge(&memcg->memsw, bytes); } /* @@ -2713,9 +2712,6 @@ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg, { unsigned long bytes = nr_pages * PAGE_SIZE; - if (mem_cgroup_is_root(memcg)) - return; - res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes); if (do_swap_account) res_counter_uncharge_until(&memcg->memsw, @@ -3994,7 +3990,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype, * replacement page, so leave it alone when phasing out the * page that is unused after the migration. */ - if (!end_migration && !mem_cgroup_is_root(memcg)) + if (!end_migration) mem_cgroup_do_uncharge(memcg, nr_pages, ctype); return memcg; @@ -4127,8 +4123,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent) * We uncharge this because swap is freed. This memcg can * be obsolete one. We avoid calling css_tryget_online(). */ - if (!mem_cgroup_is_root(memcg)) - res_counter_uncharge(&memcg->memsw, PAGE_SIZE); + res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_swap_statistics(memcg, false); css_put(&memcg->css); } @@ -4818,78 +4813,24 @@ out: return retval; } - -static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg, - enum mem_cgroup_stat_index idx) -{ - struct mem_cgroup *iter; - long val = 0; - - /* Per-cpu values can be negative, use a signed accumulator */ - for_each_mem_cgroup_tree(iter, memcg) - val += mem_cgroup_read_stat(iter, idx); - - if (val < 0) /* race ? */ - val = 0; - return val; -} - -static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) -{ - u64 val; - - if (!mem_cgroup_is_root(memcg)) { - if (!swap) - return res_counter_read_u64(&memcg->res, RES_USAGE); - else - return res_counter_read_u64(&memcg->memsw, RES_USAGE); - } - - /* - * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS - * as well as in MEM_CGROUP_STAT_RSS_HUGE. - */ - val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); - val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS); - - if (swap) - val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP); - - return val << PAGE_SHIFT; -} - static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, - struct cftype *cft) + struct cftype *cft) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); - u64 val; - int name; - enum res_type type; - - type = MEMFILE_TYPE(cft->private); - name = MEMFILE_ATTR(cft->private); + enum res_type type = MEMFILE_TYPE(cft->private); + int name = MEMFILE_ATTR(cft->private); switch (type) { case _MEM: - if (name == RES_USAGE) - val = mem_cgroup_usage(memcg, false); - else - val = res_counter_read_u64(&memcg->res, name); - break; + return res_counter_read_u64(&memcg->res, name); case _MEMSWAP: - if (name == RES_USAGE) - val = mem_cgroup_usage(memcg, true); - else - val = res_counter_read_u64(&memcg->memsw, name); - break; + return res_counter_read_u64(&memcg->memsw, name); case _KMEM: - val = res_counter_read_u64(&memcg->kmem, name); + return res_counter_read_u64(&memcg->kmem, name); break; default: BUG(); } - - return val; } #ifdef CONFIG_MEMCG_KMEM @@ -5351,7 +5292,10 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) if (!t) goto unlock; - usage = mem_cgroup_usage(memcg, swap); + if (!swap) + usage = res_counter_read_u64(&memcg->res, RES_USAGE); + else + usage = res_counter_read_u64(&memcg->memsw, RES_USAGE); /* * current_threshold points to threshold just below or equal to usage. @@ -5443,15 +5387,15 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, mutex_lock(&memcg->thresholds_lock); - if (type == _MEM) + if (type == _MEM) { thresholds = &memcg->thresholds; - else if (type == _MEMSWAP) + usage = res_counter_read_u64(&memcg->res, RES_USAGE); + } else if (type == _MEMSWAP) { thresholds = &memcg->memsw_thresholds; - else + usage = res_counter_read_u64(&memcg->memsw, RES_USAGE); + } else BUG(); - usage = mem_cgroup_usage(memcg, type == _MEMSWAP); - /* Check if a threshold crossed before adding a new one */ if (thresholds->primary) __mem_cgroup_threshold(memcg, type == _MEMSWAP); @@ -5531,18 +5475,19 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg, int i, j, size; mutex_lock(&memcg->thresholds_lock); - if (type == _MEM) + + if (type == _MEM) { thresholds = &memcg->thresholds; - else if (type == _MEMSWAP) + usage = res_counter_read_u64(&memcg->res, RES_USAGE); + } else if (type == _MEMSWAP) { thresholds = &memcg->memsw_thresholds; - else + usage = res_counter_read_u64(&memcg->memsw, RES_USAGE); + } else BUG(); if (!thresholds->primary) goto unlock; - usage = mem_cgroup_usage(memcg, type == _MEMSWAP); - /* Check if a threshold crossed before removing */ __mem_cgroup_threshold(memcg, type == _MEMSWAP); @@ -6297,9 +6242,9 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css) * core guarantees its existence. */ } else { - res_counter_init(&memcg->res, NULL); - res_counter_init(&memcg->memsw, NULL); - res_counter_init(&memcg->kmem, NULL); + res_counter_init(&memcg->res, &root_mem_cgroup->res); + res_counter_init(&memcg->memsw, &root_mem_cgroup->memsw); + res_counter_init(&memcg->kmem, &root_mem_cgroup->kmem); /* * Deeper hierachy with use_hierarchy == false doesn't make * much sense so let cgroup subsystem know about this @@ -6412,13 +6357,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css) /* Handlers for move charge at task migration. */ static int mem_cgroup_do_precharge(unsigned long count) { - int ret = 0; - - if (mem_cgroup_is_root(mc.to)) { - mc.precharge += count; - /* we don't need css_get for root */ - return ret; - } + int ret; /* Try a single bulk charge without reclaim first */ ret = mem_cgroup_try_charge(mc.to, GFP_KERNEL & ~__GFP_WAIT, count); @@ -6725,21 +6664,18 @@ static void __mem_cgroup_clear_mc(void) /* we must fixup refcnts and charges */ if (mc.moved_swap) { /* uncharge swap account from the old cgroup */ - if (!mem_cgroup_is_root(mc.from)) - res_counter_uncharge(&mc.from->memsw, - PAGE_SIZE * mc.moved_swap); + res_counter_uncharge(&mc.from->memsw, + PAGE_SIZE * mc.moved_swap); for (i = 0; i < mc.moved_swap; i++) css_put(&mc.from->css); - if (!mem_cgroup_is_root(mc.to)) { - /* - * we charged both to->res and to->memsw, so we should - * uncharge to->res. - */ - res_counter_uncharge(&mc.to->res, - PAGE_SIZE * mc.moved_swap); - } + /* + * we charged both to->res and to->memsw, so we should + * uncharge to->res. + */ + res_counter_uncharge(&mc.to->res, + PAGE_SIZE * mc.moved_swap); /* we've already done css_get(mc.to) */ mc.moved_swap = 0; } -- 2.39.5