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[209.6.122.159]) by smtp.gmail.com with ESMTPSA id r189sm1057077qke.56.2021.04.14.20.28.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Apr 2021 20:28:06 -0700 (PDT) Date: Wed, 14 Apr 2021 23:28:04 -0400 From: Masayoshi Mizuma To: Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Xing Zhengjun Subject: Re: [PATCH v3 3/5] mm/memcg: Cache vmstat data in percpu memcg_stock_pcp Message-ID: <20210415032804.kocbusnrmaambbkr@gabell> References: <20210414012027.5352-1-longman@redhat.com> <20210414012027.5352-4-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210414012027.5352-4-longman@redhat.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E0BF740002C4 X-Stat-Signature: wjbagatdhe5zqjaugoraxf99jzoz5wbm Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from=""; helo=mail-qk1-f171.google.com; client-ip=209.85.222.171 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618457284-146574 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Apr 13, 2021 at 09:20:25PM -0400, Waiman Long wrote: > Before the new slab memory controller with per object byte charging, > charging and vmstat data update happen only when new slab pages are > allocated or freed. Now they are done with every kmem_cache_alloc() > and kmem_cache_free(). This causes additional overhead for workloads > that generate a lot of alloc and free calls. > > The memcg_stock_pcp is used to cache byte charge for a specific > obj_cgroup to reduce that overhead. To further reducing it, this patch > makes the vmstat data cached in the memcg_stock_pcp structure as well > until it accumulates a page size worth of update or when other cached > data change. > > On a 2-socket Cascade Lake server with instrumentation enabled and this > patch applied, it was found that about 17% (946796 out of 5515184) of the > time when __mod_obj_stock_state() is called leads to an actual call to > mod_objcg_state() after initial boot. When doing parallel kernel build, > the figure was about 16% (21894614 out of 139780628). So caching the > vmstat data reduces the number of calls to mod_objcg_state() by more > than 80%. > > Signed-off-by: Waiman Long > Reviewed-by: Shakeel Butt > --- > mm/memcontrol.c | 78 +++++++++++++++++++++++++++++++++++++++++++------ > mm/slab.h | 26 +++++++---------- > 2 files changed, 79 insertions(+), 25 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b19100c68aa0..539c3b632e47 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2220,7 +2220,10 @@ struct memcg_stock_pcp { > > #ifdef CONFIG_MEMCG_KMEM > struct obj_cgroup *cached_objcg; > + struct pglist_data *cached_pgdat; > unsigned int nr_bytes; > + int vmstat_idx; > + int vmstat_bytes; > #endif > > struct work_struct work; > @@ -3157,6 +3160,21 @@ void __memcg_kmem_uncharge_page(struct page *page, int order) > css_put(&memcg->css); > } > > +static inline void mod_objcg_state(struct obj_cgroup *objcg, > + struct pglist_data *pgdat, > + enum node_stat_item idx, int nr) > +{ > + struct mem_cgroup *memcg; > + struct lruvec *lruvec = NULL; > + > + rcu_read_lock(); > + memcg = obj_cgroup_memcg(objcg); > + if (pgdat) > + lruvec = mem_cgroup_lruvec(memcg, pgdat); > + __mod_memcg_lruvec_state(memcg, lruvec, idx, nr); > + rcu_read_unlock(); > +} > + > static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) > { > struct memcg_stock_pcp *stock; > @@ -3207,6 +3225,14 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock) > stock->nr_bytes = 0; > } > > + if (stock->vmstat_bytes) { > + mod_objcg_state(old, stock->cached_pgdat, stock->vmstat_idx, > + stock->vmstat_bytes); > + stock->vmstat_bytes = 0; > + stock->vmstat_idx = 0; > + stock->cached_pgdat = NULL; > + } > + > obj_cgroup_put(old); > stock->cached_objcg = NULL; > } > @@ -3251,6 +3277,48 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) > local_irq_restore(flags); > } > > +static void __mod_obj_stock_state(struct obj_cgroup *objcg, > + struct pglist_data *pgdat, int idx, int nr) > +{ > + struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock); > + > + if (stock->cached_objcg != objcg) { > + /* Output the current data as is */ > + } else if (!stock->vmstat_bytes) { > + /* Save the current data */ > + stock->vmstat_bytes = nr; > + stock->vmstat_idx = idx; > + stock->cached_pgdat = pgdat; > + nr = 0; > + } else if ((stock->cached_pgdat != pgdat) || > + (stock->vmstat_idx != idx)) { > + /* Output the cached data & save the current data */ > + swap(nr, stock->vmstat_bytes); > + swap(idx, stock->vmstat_idx); > + swap(pgdat, stock->cached_pgdat); > + } else { > + stock->vmstat_bytes += nr; > + if (abs(nr) > PAGE_SIZE) { > + nr = stock->vmstat_bytes; > + stock->vmstat_bytes = 0; > + } else { > + nr = 0; > + } > + } > + if (nr) > + mod_objcg_state(objcg, pgdat, idx, nr); > +} > + > +void mod_obj_stock_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, > + int idx, int nr) > +{ > + unsigned long flags; > + > + local_irq_save(flags); > + __mod_obj_stock_state(objcg, pgdat, idx, nr); > + local_irq_restore(flags); > +} > + > int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size) > { > struct mem_cgroup *memcg; > @@ -3300,18 +3368,10 @@ void obj_cgroup_uncharge_mod_state(struct obj_cgroup *objcg, size_t size, > struct pglist_data *pgdat, int idx) > { > unsigned long flags; > - struct mem_cgroup *memcg; > - struct lruvec *lruvec = NULL; > > local_irq_save(flags); > __refill_obj_stock(objcg, size); > - > - rcu_read_lock(); > - memcg = obj_cgroup_memcg(objcg); > - if (pgdat) > - lruvec = mem_cgroup_lruvec(memcg, pgdat); > - __mod_memcg_lruvec_state(memcg, lruvec, idx, -(int)size); > - rcu_read_unlock(); > + __mod_obj_stock_state(objcg, pgdat, idx, -(int)size); > local_irq_restore(flags); > } > > diff --git a/mm/slab.h b/mm/slab.h > index 677cdc52e641..03bd9813422b 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -239,6 +239,8 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla > #ifdef CONFIG_MEMCG_KMEM > int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s, > gfp_t gfp, bool new_page); > +void mod_obj_stock_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, > + int idx, int nr); > > static inline void memcg_free_page_obj_cgroups(struct page *page) > { > @@ -283,20 +285,6 @@ static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, > return true; > } > > -static inline void mod_objcg_state(struct obj_cgroup *objcg, > - struct pglist_data *pgdat, > - enum node_stat_item idx, int nr) > -{ > - struct mem_cgroup *memcg; > - struct lruvec *lruvec; > - > - rcu_read_lock(); > - memcg = obj_cgroup_memcg(objcg); > - lruvec = mem_cgroup_lruvec(memcg, pgdat); > - mod_memcg_lruvec_state(memcg, lruvec, idx, nr); > - rcu_read_unlock(); > -} > - > static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, > struct obj_cgroup *objcg, > gfp_t flags, size_t size, > @@ -324,8 +312,9 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, > off = obj_to_index(s, page, p[i]); > obj_cgroup_get(objcg); > page_objcgs(page)[off] = objcg; > - mod_objcg_state(objcg, page_pgdat(page), > - cache_vmstat_idx(s), obj_full_size(s)); > + mod_obj_stock_state(objcg, page_pgdat(page), > + cache_vmstat_idx(s), > + obj_full_size(s)); > } else { > obj_cgroup_uncharge(objcg, obj_full_size(s)); > } > @@ -408,6 +397,11 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, > void **p, int objects) > { > } > + > +static inline void mod_obj_stock_state(struct obj_cgroup *objcg, > + struct pglist_data *pgdat, int idx, int nr) > +{ > +} > #endif /* CONFIG_MEMCG_KMEM */ > > static inline struct kmem_cache *virt_to_cache(const void *obj) > -- > 2.18.1 > Please feel free to add: Tested-by: Masayoshi Mizuma Thanks! Masa