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[37.139.156.29]) by mx.google.com with ESMTPS id y19si30637196ljh.176.2019.07.22.05.46.50 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Jul 2019 05:46:51 -0700 (PDT) Received-SPF: pass (google.com: domain of peter.enderborg@sony.com designates 37.139.156.29 as permitted sender) client-ip=37.139.156.29; Authentication-Results: mx.google.com; spf=pass (google.com: domain of peter.enderborg@sony.com designates 37.139.156.29 as permitted sender) smtp.mailfrom=Peter.Enderborg@sony.com Subject: Re: [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches To: Waiman Long , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Alexander Viro , Jonathan Corbet , Luis Chamberlain , Kees Cook , Johannes Weiner , Michal Hocko , Vladimir Davydov CC: , , , , , Roman Gushchin , Shakeel Butt , Andrea Arcangeli References: <20190702183730.14461-1-longman@redhat.com> From: peter enderborg Message-ID: <71ab6307-9484-fdd3-fe6d-d261acf7c4a5@sony.com> Date: Mon, 22 Jul 2019 14:46:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190702183730.14461-1-longman@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-GB X-SEG-SpamProfiler-Analysis: v=2.3 cv=L6RjvNb8 c=1 sm=1 tr=0 a=T5MYTZSj1jWyQccoVcawfw==:117 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=IkcTkHD0fZMA:10 a=0o9FgrsRnhwA:10 a=20KFwNOVAAAA:8 a=Z4Rwk6OoAAAA:8 a=hTz6g4Jj1mwQyzJQMEoA:9 a=QEXdDO2ut3YA:10 a=aA9c7OsbRBYA:10 a=HkZW87K1Qel5hWWM3VKY:22 X-SEG-SpamProfiler-Score: 0 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 7/2/19 8:37 PM, Waiman Long wrote: > Currently, a value of '1" is written to /sys/kernel/slab//shrink > file to shrink the slab by flushing all the per-cpu slabs and free > slabs in partial lists. This applies only to the root caches, though. > > Extends this capability by shrinking all the child memcg caches and > the root cache when a value of '2' is written to the shrink sysfs file. > > On a 4-socket 112-core 224-thread x86-64 system after a parallel kernel > build, the the amount of memory occupied by slabs before shrinking > slabs were: > > # grep task_struct /proc/slabinfo > task_struct 7114 7296 7744 4 8 : tunables 0 0 > 0 : slabdata 1824 1824 0 > # grep "^S[lRU]" /proc/meminfo > Slab: 1310444 kB > SReclaimable: 377604 kB > SUnreclaim: 932840 kB > > After shrinking slabs: > > # grep "^S[lRU]" /proc/meminfo > Slab: 695652 kB > SReclaimable: 322796 kB > SUnreclaim: 372856 kB > # grep task_struct /proc/slabinfo > task_struct 2262 2572 7744 4 8 : tunables 0 0 > 0 : slabdata 643 643 0 What is the time between this measurement points? Should not the shrinked memory show up as reclaimable? > Signed-off-by: Waiman Long > --- > Documentation/ABI/testing/sysfs-kernel-slab | 10 +++-- > mm/slab.h | 1 + > mm/slab_common.c | 43 +++++++++++++++++++++ > mm/slub.c | 2 + > 4 files changed, 52 insertions(+), 4 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab > index 29601d93a1c2..2a3d0fc4b4ac 100644 > --- a/Documentation/ABI/testing/sysfs-kernel-slab > +++ b/Documentation/ABI/testing/sysfs-kernel-slab > @@ -429,10 +429,12 @@ KernelVersion: 2.6.22 > Contact: Pekka Enberg , > Christoph Lameter > Description: > - The shrink file is written when memory should be reclaimed from > - a cache. Empty partial slabs are freed and the partial list is > - sorted so the slabs with the fewest available objects are used > - first. > + A value of '1' is written to the shrink file when memory should > + be reclaimed from a cache. Empty partial slabs are freed and > + the partial list is sorted so the slabs with the fewest > + available objects are used first. When a value of '2' is > + written, all the corresponding child memory cgroup caches > + should be shrunk as well. All other values are invalid. > > What: /sys/kernel/slab/cache/slab_size > Date: May 2007 > diff --git a/mm/slab.h b/mm/slab.h > index 3b22931bb557..a16b2c7ff4dd 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -174,6 +174,7 @@ int __kmem_cache_shrink(struct kmem_cache *); > void __kmemcg_cache_deactivate(struct kmem_cache *s); > void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s); > void slab_kmem_cache_release(struct kmem_cache *); > +int kmem_cache_shrink_all(struct kmem_cache *s); > > struct seq_file; > struct file; > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 464faaa9fd81..493697ba1da5 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -981,6 +981,49 @@ int kmem_cache_shrink(struct kmem_cache *cachep) > } > EXPORT_SYMBOL(kmem_cache_shrink); > > +/** > + * kmem_cache_shrink_all - shrink a cache and all its memcg children > + * @s: The root cache to shrink. > + * > + * Return: 0 if successful, -EINVAL if not a root cache > + */ > +int kmem_cache_shrink_all(struct kmem_cache *s) > +{ > + struct kmem_cache *c; > + > + if (!IS_ENABLED(CONFIG_MEMCG_KMEM)) { > + kmem_cache_shrink(s); > + return 0; > + } > + if (!is_root_cache(s)) > + return -EINVAL; > + > + /* > + * The caller should have a reference to the root cache and so > + * we don't need to take the slab_mutex. We have to take the > + * slab_mutex, however, to iterate the memcg caches. > + */ > + get_online_cpus(); > + get_online_mems(); > + kasan_cache_shrink(s); > + __kmem_cache_shrink(s); > + > + mutex_lock(&slab_mutex); > + for_each_memcg_cache(c, s) { > + /* > + * Don't need to shrink deactivated memcg caches. > + */ > + if (s->flags & SLAB_DEACTIVATED) > + continue; > + kasan_cache_shrink(c); > + __kmem_cache_shrink(c); > + } > + mutex_unlock(&slab_mutex); > + put_online_mems(); > + put_online_cpus(); > + return 0; > +} > + > bool slab_is_available(void) > { > return slab_state >= UP; > diff --git a/mm/slub.c b/mm/slub.c > index a384228ff6d3..5d7b0004c51f 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -5298,6 +5298,8 @@ static ssize_t shrink_store(struct kmem_cache *s, > { > if (buf[0] == '1') > kmem_cache_shrink(s); > + else if (buf[0] == '2') > + kmem_cache_shrink_all(s); > else > return -EINVAL; > return length;