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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 4E9EBC43381 for ; Fri, 22 Mar 2019 22:49:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1126921B18 for ; Fri, 22 Mar 2019 22:49:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="dzOycvFR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728405AbfCVWtv (ORCPT ); Fri, 22 Mar 2019 18:49:51 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:36842 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727918AbfCVWtt (ORCPT ); Fri, 22 Mar 2019 18:49:49 -0400 Received: by mail-wm1-f67.google.com with SMTP id h18so3626860wml.1 for ; Fri, 22 Mar 2019 15:49:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Y9aDRaeIImkqbs3RD6gMjzp9RFeZ93eNkXfZogPMzV4=; b=dzOycvFR3LXcdAJzc1cZuTdB5YuJ4celv5OXmLq76bC6fhuIRBXXymUZ2X1e4X3GPz g+RHtQxVTPHKrMHRvLhSlNJtytCLr+c/sSTjz6Ejtz9K6fAOuiJqD90x+aTB17NOUbU2 C2jzjifh8zT6akDauo5+bFHj33WXlPFIZB7+0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Y9aDRaeIImkqbs3RD6gMjzp9RFeZ93eNkXfZogPMzV4=; b=t4pNThUn0jwDN8OMGttHLF6aDFH0eOlpK2vr+U+4bOpgMfc1NKkfQqV7+YJhtIxKAv JQgyWAlQG3391QNqkkMNpPKR2WMrRtbbVX7njYE9+xOSAGcvuyE3B3q+pbRXDk533IrJ MEwJE8tQWz2wdMa8aD0VaMY6wsdyaVpE/I/g1s8zhHuqz36YvSjvWUylqP0dDq32gNkm GsYP7IT3xjIYWo0u8y5/mGjZXXTrDNK6V2PJAqRXKkq/JDuFQksyLExVu3lXNQkqKwhx dijNjjUrkIkYPFtLRgkLW+iz9fIZqJfWrh4rDMSPrNfLQpdyZsE/M1aOWQdIbHxWj5Hx 2Lig== X-Gm-Message-State: APjAAAVy2rMZ8EjwpIyNMttcLcferBi18M51scrIvpcO2zevOqLMgw6f skV26QSLE5yk7HIVvnaGy3J0rg== X-Google-Smtp-Source: APXvYqwdz61zVqNkLMZqtOFJF0lk6vAo9J3Kz5QBK9eFpbbP8HIiqceSQ3TxUDoETV5aA9ODpBzhFQ== X-Received: by 2002:a1c:ac87:: with SMTP id v129mr4695169wme.72.1553294987958; Fri, 22 Mar 2019 15:49:47 -0700 (PDT) Received: from localhost ([89.36.66.5]) by smtp.gmail.com with ESMTPSA id u12sm9138257wrt.2.2019.03.22.15.49.47 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 22 Mar 2019 15:49:47 -0700 (PDT) Date: Fri, 22 Mar 2019 22:49:46 +0000 From: Chris Down To: Roman Gushchin Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Tejun Heo , Dennis Zhou , "linux-kernel@vger.kernel.org" , "cgroups@vger.kernel.org" , "linux-mm@kvack.org" , Kernel Team Subject: Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude protection Message-ID: <20190322224946.GA12527@chrisdown.name> References: <20190228213050.GA28211@chrisdown.name> <20190322160307.GA3316@chrisdown.name> <20190322222907.GA17496@tower.DHCP.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20190322222907.GA17496@tower.DHCP.thefacebook.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Roman Gushchin writes: >I've noticed that the old version is just wrong: if cgroup_size is way smaller >than max(min, low), scan will be set to -lruvec_size. >Given that it's unsigned long, we'll end up with scanning the whole list >(due to clamp() below). Are you certain? If so, I don't see what you mean. This is how the code looks in Linus' tree after the fixups: unsigned long cgroup_size = mem_cgroup_size(memcg); unsigned long baseline = 0; if (!sc->memcg_low_reclaim) baseline = lruvec_size; scan = lruvec_size * cgroup_size / protection - baseline; This works correctly as far as I can tell: low reclaim case: In [1]: cgroup_size=50; lruvec_size=10; protection=2000; baseline=0; lruvec_size * cgroup_size // protection - baseline Out[1]: 0 normal case: In [2]: cgroup_size=3000; lruvec_size=10; protection=2000; baseline=lruvec_size; lruvec_size * cgroup_size // protection - baseline Out[2]: 5