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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 02170C11D20 for ; Thu, 20 Feb 2020 20:54:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB0E920679 for ; Thu, 20 Feb 2020 20:54:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582232062; bh=csklF/VLfMBe/9AbLqcIGNOh+eIVqt00sLyRiNBn9xQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dKq3DuEZhpT5ew0NUv5/WIlJuTaL+VIbow5qnG2eYeXKvI28BrWzm5cxE+U1OQgca tvETzCRcZ1UGB3PotULXrPtIc8E6PKaU5ca3z+eC7K279/sOi6m+1JxWC7ngUZxpnT JdKYJO8Tpcl3KUgB2vw6N1gQ4CXrm0olCmfX9RjA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729150AbgBTUyV (ORCPT ); Thu, 20 Feb 2020 15:54:21 -0500 Received: from mail-qt1-f193.google.com ([209.85.160.193]:43304 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728400AbgBTUyU (ORCPT ); Thu, 20 Feb 2020 15:54:20 -0500 Received: by mail-qt1-f193.google.com with SMTP id g21so3913620qtq.10; Thu, 20 Feb 2020 12:54:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=BiE+rct0rry2pArV3gigMdzlZiS1+memMy+VBdXCC0g=; b=oHWDw6RCZdv06TZrh3Qj3gsEIXivcxE3uXPCbkcJ2m2UdQNHxxKuovATMPLuouJjWG /7xptXQ03FED86Sla82047upyBEwI7HZBrTJXMer3p1NaCTwIpl16i4cOA7FPSFwwncS RUIp1/jottGogriZOzdHOi3HyT61dDWUWxDebE8ZiGPJ2NkCjmgm+shlmh5wd83Qzy3Z 30286SGALzQD8SzVxnEet57ytjDAmy8YcnYLI48M4clrruxKdKnmO6MIgs507n5itrye 6TpiJZ0fBNrb2OL9NGL+NJLlTWEAMfP3nSPcOxps//7VAMRGHfh2t/E95u0WyPTdwj5R ChBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=BiE+rct0rry2pArV3gigMdzlZiS1+memMy+VBdXCC0g=; b=Q7KXVyVHwypRtv42tH2ru772XVRri88IxIn7uIHPpYUKHUnDNybvquoP3iQIN4jszQ +CYYc7GSXncDupngtB6jHugNG1+/zWkTV5qZxvMzks145KBexzHUHqWLcOr3iHg2H33x khXLL7p6yviQLBR9ZKU7V6lBGsH8BlY/xmgBky6q0CnegFexeVsyxdK9+N8e5QOYUrCT ByZ9Cc3yrw5fEGzDRHc9xOObqgqukmX3KxGIaRhJYnH+o5sbpU8OVkmaU4Coqy7QgdPW DN9l3Une9E5cjLYykJuXxYJroSQ0lRPLjWs19n+oLekA6BEbFSQVRhFf/DUItUVCxyMg QE2g== X-Gm-Message-State: APjAAAXVYdhXARrzBr8LOe1Rof32SYngJn9G+bvvmOiQhrL26bpmV88A DlbzDtoE7ngLOrU0kf3ISsA= X-Google-Smtp-Source: APXvYqx8p0C/GaJD7Fie8OUeewsrbm4Q0PH7AogGZxTkl86op5vkJ3JFVQfhBK9/2ANYRUN8ev8xbA== X-Received: by 2002:aed:3f70:: with SMTP id q45mr27822085qtf.310.1582232057881; Thu, 20 Feb 2020 12:54:17 -0800 (PST) Received: from localhost ([2620:10d:c091:500::55b1]) by smtp.gmail.com with ESMTPSA id g9sm420153qkl.11.2020.02.20.12.54.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2020 12:54:17 -0800 (PST) Date: Thu, 20 Feb 2020 15:54:16 -0500 From: Tejun Heo To: Daniel Jordan Cc: Johannes Weiner , Michal Hocko , Andrew Morton , Roman Gushchin , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Peter Zijlstra Subject: Re: [PATCH] mm: memcontrol: asynchronous reclaim for memory.high Message-ID: <20200220205416.GI698990@mtj.thefacebook.com> References: <20200219183731.GC11847@dhcp22.suse.cz> <20200219191618.GB54486@cmpxchg.org> <20200219195332.GE11847@dhcp22.suse.cz> <20200219214112.4kt573kyzbvmbvn3@ca-dmjordan1.us.oracle.com> <20200219220859.GF54486@cmpxchg.org> <20200220154524.dql3i5brnjjwecft@ca-dmjordan1.us.oracle.com> <20200220155651.GG698990@mtj.thefacebook.com> <20200220182326.ubcjycaubgykiy6e@ca-dmjordan1.us.oracle.com> <20200220184545.GH698990@mtj.thefacebook.com> <20200220195535.7xblt45akld6eftj@ca-dmjordan1.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200220195535.7xblt45akld6eftj@ca-dmjordan1.us.oracle.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Daniel. On Thu, Feb 20, 2020 at 02:55:35PM -0500, Daniel Jordan wrote: > On Thu, Feb 20, 2020 at 01:45:45PM -0500, Tejun Heo wrote: > > The setup cost can be lazy optimized but it'd still have to bounce the > > tiny pieces of work to different threads instead of processing them in > > one fell swoop from the same context, which most likely is gonna be > > untenably expensive. > > I see, your last mail is clearer now. If it's easy to do, a pointer to where > this happens would help so we're on the same page. Network packet rx is the clearest example I think, but you already mentioned it. Reclaim is less so but when kswapd reclaims, it walks everybody, and there can be a lot of small cgroups. Thanks. -- tejun