linux-kernel - Re: [RFC][PATCH] oom: Be less verbose if the oom

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Message-ID: <5390930A.8050504@nod.at>
Date:	Thu, 05 Jun 2014 17:55:54 +0200
From:	Richard Weinberger <richard@....at>
To:	Michal Hocko <mhocko@...e.cz>
CC:	hannes@...xchg.org, bsingharora@...il.com,
	kamezawa.hiroyu@...fujitsu.com, akpm@...ux-foundation.org,
	vdavydov@...allels.com, tj@...nel.org, handai.szj@...bao.com,
	rientjes@...gle.com, oleg@...hat.com, rusty@...tcorp.com.au,
	kirill.shutemov@...ux.intel.com, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC][PATCH] oom: Be less verbose if the oom_control event fd
 has listeners

Am 05.06.2014 17:00, schrieb Michal Hocko:
> On Thu 05-06-14 16:00:41, Richard Weinberger wrote:
>> Don't spam the kernel logs if the oom_control event fd has listeners.
>> In this case there is no need to print that much lines as user space
>> will anyway notice that the memory cgroup has reached its limit.
> 
> But how do you debug why it is reaching the limit and why a particular
> process has been killed?

In my case it's always because customer's Java application gone nuts.
So I don't really have to debug a lot. ;-)
But I can understand your point.

> If we are printing too much then OK, let's remove those parts which are
> not that useful but hiding information which tells us more about the oom
> decision doesn't sound right to me.

What about adding a sysctl like "vm.oom_verbose"?
By default it would be 1.
If set to 0 the full OOM information is only printed out if nobody listens
to the event fd.

Thanks,
//richard
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