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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 A54B3C6778C for ; Tue, 3 Jul 2018 20:58:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63C3B24772 for ; Tue, 3 Jul 2018 20:58:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63C3B24772 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753155AbeGCU6R (ORCPT ); Tue, 3 Jul 2018 16:58:17 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43856 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752719AbeGCU6P (ORCPT ); Tue, 3 Jul 2018 16:58:15 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.9.92]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id A82B0D5D; Tue, 3 Jul 2018 20:58:14 +0000 (UTC) Date: Tue, 3 Jul 2018 13:58:13 -0700 From: Andrew Morton To: Kirill Tkhai Cc: vdavydov.dev@gmail.com, shakeelb@google.com, viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.org, tglx@linutronix.de, pombredanne@nexb.com, stummala@codeaurora.org, gregkh@linuxfoundation.org, sfr@canb.auug.org.au, guro@fb.com, mka@chromium.org, penguin-kernel@I-love.SAKURA.ne.jp, chris@chris-wilson.co.uk, longman@redhat.com, minchan@kernel.org, ying.huang@intel.com, mgorman@techsingularity.net, jbacik@fb.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, lirongqing@baidu.com, aryabinin@virtuozzo.com Subject: Re: [PATCH v8 14/17] mm: Iterate only over charged shrinkers during memcg shrink_slab() Message-Id: <20180703135813.ed4eef6a4a2df32fa1085e4c@linux-foundation.org> In-Reply-To: <153063066653.1818.976035462801487910.stgit@localhost.localdomain> References: <153063036670.1818.16010062622751502.stgit@localhost.localdomain> <153063066653.1818.976035462801487910.stgit@localhost.localdomain> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 03 Jul 2018 18:11:06 +0300 Kirill Tkhai wrote: > Using the preparations made in previous patches, in case of memcg > shrink, we may avoid shrinkers, which are not set in memcg's shrinkers > bitmap. To do that, we separate iterations over memcg-aware and > !memcg-aware shrinkers, and memcg-aware shrinkers are chosen > via for_each_set_bit() from the bitmap. In case of big nodes, > having many isolated environments, this gives significant > performance growth. See next patches for the details. > > Note, that the patch does not respect to empty memcg shrinkers, > since we never clear the bitmap bits after we set it once. > Their shrinkers will be called again, with no shrinked objects > as result. This functionality is provided by next patches. > > ... > > @@ -541,6 +555,67 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > return freed; > } > > +#ifdef CONFIG_MEMCG_KMEM > +static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, > + struct mem_cgroup *memcg, int priority) > +{ > + struct memcg_shrinker_map *map; > + unsigned long freed = 0; > + int ret, i; > + > + if (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)) > + return 0; > + > + if (!down_read_trylock(&shrinker_rwsem)) > + return 0; Why trylock? Presumably some other code path is known to hold the lock for long periods? Dunno. Comment it, please. > + /* > + * 1) Caller passes only alive memcg, so map can't be NULL. > + * 2) shrinker_rwsem protects from maps expanding. > + */ > + map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map, > + true); > + BUG_ON(!map); > + > + for_each_set_bit(i, map->map, shrinker_nr_max) { > + struct shrink_control sc = { > + .gfp_mask = gfp_mask, > + .nid = nid, > + .memcg = memcg, > + }; > + struct shrinker *shrinker; > + > + shrinker = idr_find(&shrinker_idr, i); > + if (unlikely(!shrinker)) { > + clear_bit(i, map->map); > + continue; > + } > + BUG_ON(!(shrinker->flags & SHRINKER_MEMCG_AWARE)); Fair enough as a development-time sanity check but we shouldn't need this in production code. Or make it VM_BUG_ON(), at least. > + /* See comment in prealloc_shrinker() */ > + if (unlikely(list_empty(&shrinker->list))) > + continue; > + > + ret = do_shrink_slab(&sc, shrinker, priority); > + freed += ret; > + > + if (rwsem_is_contended(&shrinker_rwsem)) { > + freed = freed ? : 1; > + break; > + } > + } > + > + up_read(&shrinker_rwsem); > + return freed; > +}