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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 3CC64C4743E for ; Tue, 8 Jun 2021 08:55:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A531361285 for ; Tue, 8 Jun 2021 08:55:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A531361285 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 051E76B0078; Tue, 8 Jun 2021 04:55:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0299F6B007B; Tue, 8 Jun 2021 04:55:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E33AC6B007D; Tue, 8 Jun 2021 04:55:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0023.hostedemail.com [216.40.44.23]) by kanga.kvack.org (Postfix) with ESMTP id B656E6B0078 for ; Tue, 8 Jun 2021 04:55:00 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4BCB2180AD802 for ; Tue, 8 Jun 2021 08:55:00 +0000 (UTC) X-FDA: 78229946760.04.3A4D88A Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf24.hostedemail.com (Postfix) with ESMTP id 7F95DA000240 for ; Tue, 8 Jun 2021 08:54:56 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id B06401FD2A; Tue, 8 Jun 2021 08:54:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1623142498; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=s57GF5EVrU8EkU6hVgTxTv92JSfKxB+kZ8XzRaWUnBM=; b=dMUn34jq76iZfpe+e/UvfR64NqfiyE3bGkAnY7c5GBBn26baRgLDP3PSf/g+WNPP6nOAh3 wxNlk4Q/cxIYWdmJZh48684o9Ycgg0G8kmQFLnQFdkIYRoOluOboCH4yj01stu5xe6fkZw n3WP11Zr8PmwFcRZ/QM2wsIbAoeJNFY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1623142498; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=s57GF5EVrU8EkU6hVgTxTv92JSfKxB+kZ8XzRaWUnBM=; b=QB67RQ6oO8NzzFxSr5nVeyP4+sAxevwN2dFw2I9h2gNFohGorTS0PXXTrCglCxi/x2Cy7D qc3kQ5g6XNatMDAQ== Received: from quack2.suse.cz (unknown [10.100.200.198]) by relay2.suse.de (Postfix) with ESMTP id A7FFAA3B83; Tue, 8 Jun 2021 08:54:58 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 5F9E21F2C94; Tue, 8 Jun 2021 10:54:58 +0200 (CEST) Date: Tue, 8 Jun 2021 10:54:58 +0200 From: Jan Kara To: Roman Gushchin Cc: Jan Kara , Tejun Heo , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , Dennis Zhou , Dave Chinner , cgroups@vger.kernel.org Subject: Re: [PATCH v8 8/8] writeback, cgroup: release dying cgwbs by switching attached inodes Message-ID: <20210608085458.GC5562@quack2.suse.cz> References: <20210608013123.1088882-1-guro@fb.com> <20210608013123.1088882-9-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210608013123.1088882-9-guro@fb.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7F95DA000240 X-Stat-Signature: 61cmq341niu55o7tpchzitxwj56ikqg6 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=dMUn34jq; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=QB67RQ6o; dmarc=none; spf=pass (imf24.hostedemail.com: domain of jack@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=jack@suse.cz X-HE-Tag: 1623142496-845814 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 Mon 07-06-21 18:31:23, Roman Gushchin wrote: > Asynchronously try to release dying cgwbs by switching attached inodes > to the nearest living ancestor wb. It helps to get rid of per-cgroup > writeback structures themselves and of pinned memory and block cgroups, > which are significantly larger structures (mostly due to large per-cpu > statistics data). This prevents memory waste and helps to avoid > different scalability problems caused by large piles of dying cgroups. > > Reuse the existing mechanism of inode switching used for foreign inode > detection. To speed things up batch up to 115 inode switching in a > single operation (the maximum number is selected so that the resulting > struct inode_switch_wbs_context can fit into 1024 bytes). Because > every switching consists of two steps divided by an RCU grace period, > it would be too slow without batching. Please note that the whole > batch counts as a single operation (when increasing/decreasing > isw_nr_in_flight). This allows to keep umounting working (flush the > switching queue), however prevents cleanups from consuming the whole > switching quota and effectively blocking the frn switching. > > A cgwb cleanup operation can fail due to different reasons (e.g. not > enough memory, the cgwb has an in-flight/pending io, an attached inode > in a wrong state, etc). In this case the next scheduled cleanup will > make a new attempt. An attempt is made each time a new cgwb is offlined > (in other words a memcg and/or a blkcg is deleted by a user). In the > future an additional attempt scheduled by a timer can be implemented. > > Signed-off-by: Roman Gushchin > Acked-by: Tejun Heo > Acked-by: Dennis Zhou The patch looks good. Feel free to add: Reviewed-by: Jan Kara Just one codingstyle nit below. > + if (!wb_tryget(wb)) > + continue; > + > + spin_unlock_irq(&cgwb_lock); > + while ((cleanup_offline_cgwb(wb))) ^^ too many parentheses here... > + cond_resched(); > + spin_lock_irq(&cgwb_lock); Honza -- Jan Kara SUSE Labs, CR