linux-kernel - Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when unreclaimable slabs

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Message-ID: <20171019072809.xykifzpsiabdjv6m@dhcp22.suse.cz>
Date:   Thu, 19 Oct 2017 09:28:09 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Yang Shi <yang.s@...baba-inc.com>, cl@...ux.com,
        penberg@...nel.org, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when
 unreclaimable slabs > user memory

On Tue 17-10-17 15:39:08, David Rientjes wrote:
> On Wed, 18 Oct 2017, Yang Shi wrote:
> 
> > > Yes, this should catch occurrences of "huge unreclaimable slabs", right?
> > 
> > Yes, it sounds so. Although single "huge" unreclaimable slab might not result
> > in excessive slabs use in a whole, but this would help to filter out "small"
> > unreclaimable slab.
> > 
> 
> Keep in mind this is regardless of SLAB_RECLAIM_ACCOUNT: your patch has 
> value beyond only unreclaimable slab, it can also be used to show 
> instances where the oom killer was invoked without properly reclaiming 
> slab.  If the total footprint of a slab cache exceeds 5%, I think a line 
> should be emitted unconditionally to the kernel log.

agreed. I am not sure 5% is the greatest fit but we can tune that later.

-- 
Michal Hocko
SUSE Labs