All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: Roman Gushchin <guro@fb.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	kernel-team@fb.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH] mm,oom: add tracepoints for oom reaper-related events
Date: Tue, 30 May 2017 15:45:53 +0200	[thread overview]
Message-ID: <20170530134552.GI7969@dhcp22.suse.cz> (raw)
In-Reply-To: <20170530133335.GB28148@castle>

On Tue 30-05-17 14:33:35, Roman Gushchin wrote:
> On Tue, May 30, 2017 at 02:34:16PM +0200, Michal Hocko wrote:
> > On Tue 30-05-17 13:05:32, Roman Gushchin wrote:
> > > Add tracepoints to simplify the debugging of the oom reaper code.
> > > 
> > > Trace the following events:
> > > 1) a process is marked as an oom victim,
> > > 2) a process is added to the oom reaper list,
> > > 3) the oom reaper starts reaping process's mm,
> > > 4) the oom reaper finished reaping,
> > > 5) the oom reaper skips reaping.
> > 
> > I am not against but could you explain why the current printks are not
> > sufficient? We do not have any explicit printk for the 2) and 3) but
> > are those really necessary?
> 
> We also don't have any printks for 1) and 2) if, for, instance, we call
> out_of_memory() and task_will_free_mem(current) returns true.
> 
> > 
> > In other words could you describe the situation when you found these
> > tracepoints more useful than what the kernel log offers already?
> 
> During my work on cgroup-aware OOM killer and some issues discovered
> in process (which are described in https://lkml.org/lkml/2017/5/17/542;
> most important problem fixed by Tetsuo), I've found an existing debug output
> insufficient and sometimes too bulky.
> 
> Suggested traces allowed me to debug issues like I've met (double invocation
> of oom_reaper, etc) much easier.

Please describe those and examples how the new tracepoints will be
useful in the changelog.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Roman Gushchin <guro@fb.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	kernel-team@fb.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH] mm,oom: add tracepoints for oom reaper-related events
Date: Tue, 30 May 2017 15:45:53 +0200	[thread overview]
Message-ID: <20170530134552.GI7969@dhcp22.suse.cz> (raw)
In-Reply-To: <20170530133335.GB28148@castle>

On Tue 30-05-17 14:33:35, Roman Gushchin wrote:
> On Tue, May 30, 2017 at 02:34:16PM +0200, Michal Hocko wrote:
> > On Tue 30-05-17 13:05:32, Roman Gushchin wrote:
> > > Add tracepoints to simplify the debugging of the oom reaper code.
> > > 
> > > Trace the following events:
> > > 1) a process is marked as an oom victim,
> > > 2) a process is added to the oom reaper list,
> > > 3) the oom reaper starts reaping process's mm,
> > > 4) the oom reaper finished reaping,
> > > 5) the oom reaper skips reaping.
> > 
> > I am not against but could you explain why the current printks are not
> > sufficient? We do not have any explicit printk for the 2) and 3) but
> > are those really necessary?
> 
> We also don't have any printks for 1) and 2) if, for, instance, we call
> out_of_memory() and task_will_free_mem(current) returns true.
> 
> > 
> > In other words could you describe the situation when you found these
> > tracepoints more useful than what the kernel log offers already?
> 
> During my work on cgroup-aware OOM killer and some issues discovered
> in process (which are described in https://lkml.org/lkml/2017/5/17/542;
> most important problem fixed by Tetsuo), I've found an existing debug output
> insufficient and sometimes too bulky.
> 
> Suggested traces allowed me to debug issues like I've met (double invocation
> of oom_reaper, etc) much easier.

Please describe those and examples how the new tracepoints will be
useful in the changelog.
-- 
Michal Hocko
SUSE Labs

--
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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2017-05-30 13:45 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-30 12:05 [PATCH] mm,oom: add tracepoints for oom reaper-related events Roman Gushchin
2017-05-30 12:05 ` Roman Gushchin
2017-05-30 12:34 ` Michal Hocko
2017-05-30 12:34   ` Michal Hocko
2017-05-30 13:17   ` Tetsuo Handa
2017-05-30 13:17     ` Tetsuo Handa
2017-05-30 13:33   ` Roman Gushchin
2017-05-30 13:33     ` Roman Gushchin
2017-05-30 13:45     ` Michal Hocko [this message]
2017-05-30 13:45       ` Michal Hocko
2017-05-30 18:52       ` [PATCH v2] " Roman Gushchin
2017-05-30 18:52         ` Roman Gushchin
2017-05-31 16:39         ` Michal Hocko
2017-05-31 16:39           ` Michal Hocko
2017-06-01 18:41           ` Roman Gushchin
2017-06-01 18:41             ` Roman Gushchin
2017-06-02  8:13             ` Michal Hocko
2017-06-02  8:13               ` Michal Hocko
2017-06-20 13:43               ` Roman Gushchin
2017-06-20 13:43                 ` Roman Gushchin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170530134552.GI7969@dhcp22.suse.cz \
    --to=mhocko@kernel.org \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=vdavydov.dev@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.