linux-kernel - Re: [PATCH 2/2] scripts: add kmemleak2pprof.py for slab usage analysis

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Message-Id: <20180830172105.3f30f3831c370f51e2067a6c@linux-foundation.org>
Date:   Thu, 30 Aug 2018 17:21:05 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     catalin.marinas@....com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 2/2] scripts: add kmemleak2pprof.py for slab usage
 analysis

On Thu, 30 Aug 2018 09:29:40 +0200 Vincent Whitchurch <vincent.whitchurch@...s.com> wrote:

> On Tue, Aug 28, 2018 at 04:28:04PM -0700, Andrew Morton wrote:
> > On Tue, 28 Aug 2018 12:39:14 +0200 Vincent Whitchurch <vincent.whitchurch@...s.com> wrote:
> > 
> > > Add a script which converts /sys/kernel/debug/kmemleak_all to the pprof
> > > format, which can be used for analysing memory usage.  See
> > > https://github.com/google/pprof.
> > 
> > Why is this better than /proc/slabinfo?
> 
> slabinfo just tells you how much memory is being used in a particular
> slab, it doesn't give you a breakdown of who allocated all that memory.
> slabinfo can't also tell you how much memory a particular subsystem is
> using.
> 
> For example, here we can see that tracer_init_tracefs() and its callers
> are using ~12% of the total tracked memory:
> 
>  $ pprof -top -compact_labels -cum prof 
>  Showing nodes accounting for 13418.95kB, 92.07% of 14575.28kB total
>  Dropped 4069 nodes (cum <= 72.88kB)
>        flat  flat%   sum%        cum   cum%
>        ...
>           0     0% 56.71%  1832.15kB 12.57%  tracer_init_tracefs+0x74/0x1cc
> 
>  
> And that tracefs' dentrys use 500 KiB and its inodes use 1+ MiB:
>  	
>  $ pprof -text -compact_labels -focus tracer_init_tracefs -nodecount 2 prof
>  Main binary filename not available.
>  Showing nodes accounting for 1794.85kB, 12.31% of 14575.28kB total
>  Dropped 1912 nodes (cum <= 72.88kB)
>  Showing top 2 nodes out of 32
>        flat  flat%   sum%        cum   cum%
>   1294.56kB  8.88%  8.88%  1294.56kB  8.88%  new_inode_pseudo+0x8/0x4c
>    500.29kB  3.43% 12.31%   500.29kB  3.43%  d_alloc+0x10/0x78
>    ...

OK, thanks.  Please include this info in future changelogs?