From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82076C06510 for ; Tue, 2 Jul 2019 19:15:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 665B22186A for ; Tue, 2 Jul 2019 19:15:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727104AbfGBTP4 (ORCPT ); Tue, 2 Jul 2019 15:15:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59030 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbfGBTPz (ORCPT ); Tue, 2 Jul 2019 15:15:55 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 25FA9C057F2E; Tue, 2 Jul 2019 19:15:50 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-160.bos.redhat.com [10.18.17.160]) by smtp.corp.redhat.com (Postfix) with ESMTP id AA0471347B; Tue, 2 Jul 2019 19:15:42 +0000 (UTC) Subject: Re: [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches To: David Rientjes Cc: Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Alexander Viro , Jonathan Corbet , Luis Chamberlain , Kees Cook , Johannes Weiner , Michal Hocko , Vladimir Davydov , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Roman Gushchin , Shakeel Butt , Andrea Arcangeli References: <20190702183730.14461-1-longman@redhat.com> From: Waiman Long Organization: Red Hat Message-ID: <34af4938-f472-9d9b-e615-397217023004@redhat.com> Date: Tue, 2 Jul 2019 15:15:42 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 02 Jul 2019 19:15:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/19 3:09 PM, David Rientjes wrote: > On Tue, 2 Jul 2019, Waiman Long wrote: > >> 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. >> > This should likely call out that '2' also does '1', that might not be > clear enough. You are right. I will reword the text to make it clearer. >> 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; > I'm wondering how long this could take, i.e. how long we hold slab_mutex > while we traverse each cache and shrink it. It will depends on how many memcg caches are there. Actually, I have been thinking about using the show method to show the time spent in the last shrink operation. I am just not sure if it is worth doing. What do you think? -Longman