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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 4ABF5C4727D for ; Tue, 22 Sep 2020 10:01:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D190D2084C for ; Tue, 22 Sep 2020 10:01:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="bvB8VbMc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726583AbgIVKB4 (ORCPT ); Tue, 22 Sep 2020 06:01:56 -0400 Received: from mx2.suse.de ([195.135.220.15]:37456 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgIVKBz (ORCPT ); Tue, 22 Sep 2020 06:01:55 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1600768914; h=from:from:reply-to:subject:subject: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=QLO3suN0B5LIt4PxRcxRdNDdQcD9omAqbXVobcJQit0=; b=bvB8VbMcv76lg7v+mTn3uy5QgST4NRQnUu47qUNl8D+fm1OVsZ7ir5iOajEgMTc5mRolsx +JdjG1UKUAcMkTR1JPArn3y+yQ4W+XuUYFTGDk2Xl/4Whb68KND0i+avmivAL2Jgd2GPke OFEuWW6aD69MpOK/i3dMkpRkCKNKoZU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B9B66B1AD; Tue, 22 Sep 2020 10:02:30 +0000 (UTC) Date: Tue, 22 Sep 2020 12:01:52 +0200 From: Michal Hocko To: Yafang Shao Cc: zangchunxin@bytedance.com, Johannes Weiner , Vladimir Davydov , Andrew Morton , Tejun Heo , lizefan@huawei.com, Jonathan Corbet , Alexei Starovoitov , Daniel Borkmann , kafai@fb.com, Song Liu , Yonghong Song , andriin@fb.com, john.fastabend@gmail.com, kpsingh@chromium.org, Cgroups , linux-doc@vger.kernel.org, Linux MM , LKML , netdev , bpf@vger.kernel.org Subject: Re: [PATCH] mm/memcontrol: Add the drop_cache interface for cgroup v2 Message-ID: <20200922100152.GW12990@dhcp22.suse.cz> References: <20200921080255.15505-1-zangchunxin@bytedance.com> <20200921081200.GE12990@dhcp22.suse.cz> <20200921110505.GH12990@dhcp22.suse.cz> <20200921113646.GJ12990@dhcp22.suse.cz> <20200922072733.GT12990@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 22-09-20 16:06:31, Yafang Shao wrote: > On Tue, Sep 22, 2020 at 3:27 PM Michal Hocko wrote: [...] > > What is the latency triggered by the memory reclaim? It should be mostly > > a clean page cache right as drop_caches only drops clean pages. Or is > > this more about [id]cache? Do you have any profiles where is the time > > spent? > > > > Yes, we have analyzed the issues in the direct reclaim, but that is > not the point. Are those fixed? > The point is that each case may take us several days to analyze, while > the user can't wait, so they will use drop_caches to workaround it > until we find the solution. As I've said there are several options to achieve an immediate action. Careful resource domains configuration will certainly help with that. -- Michal Hocko SUSE Labs