From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 36AA06B0398 for ; Fri, 17 Mar 2017 21:30:55 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id y6so134830011pfa.3 for ; Fri, 17 Mar 2017 18:30:55 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id 34si10234099plz.66.2017.03.17.18.30.53 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 17 Mar 2017 18:30:54 -0700 (PDT) Subject: Re: DOM Worker: page allocation stalls (4.9.13) From: Tetsuo Handa References: <20170316100409.GR802@shells.gnugeneration.com> <20170317084652.GD26298@dhcp22.suse.cz> <08ae9fca-9388-1f8a-f8ae-14ada0bdbb92@I-love.SAKURA.ne.jp> <20170317135440.GJ26298@dhcp22.suse.cz> In-Reply-To: <20170317135440.GJ26298@dhcp22.suse.cz> Message-Id: <201703181030.DII52105.FOQSVHFOFMOLJt@I-love.SAKURA.ne.jp> Date: Sat, 18 Mar 2017 10:30:46 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org Cc: elektron@halo.nu, linux-mm@kvack.org Michal Hocko wrote: > > If you can rebuild your kernel, calling dump_tasks() in mm/oom_kill.c when > > you hit warn_alloc() warnings might help. > > I do not really see how this would help much. If anything watching for > /proc/vmstat counters would tell us much more. Under memory pressure, read()/write() syscalls might involve significant delay (including reading from /sys/kernel/debug/tracing/trace_pipe and writing to a log file). Unless all problems are contained in a cgroup (which means that administrators can diagnose from outside of that cgroup), it is silly to try to read memory related information of a stalling system using userspace interface. Therefore, automatic printk() is helpful than trying to start "cat /proc/vmstat" from a shell. I wish there is a kernel function which does "cat /proc/some_file" and/or "cat /sys/kernel/debug/tracing/trace_pipe" and sends the output to printk() so that such actions will not involve significant delay under memory pressure. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org