linux-kernel - Re: [RFC] scripts: Include postprocessing script for memory allocation tracing

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Date:   Thu, 22 Sep 2016 11:30:36 -0400
From:   Janani Ravichandran <janani.rvchndrn@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Janani Ravichandran <janani.rvchndrn@...il.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, riel@...riel.com,
        akpm@...ux-foundation.org, vdavydov@...tuozzo.com, vbabka@...e.cz,
        mgorman@...hsingularity.net, rostedt@...dmis.org
Subject: Re: [RFC] scripts: Include postprocessing script for memory allocation tracing


> On Sep 19, 2016, at 5:42 AM, Michal Hocko <mhocko@...nel.org> wrote:
> 
> On Tue 13-09-16 14:04:49, Janani Ravichandran wrote:
>> 
>>> On Sep 12, 2016, at 8:16 AM, Michal Hocko <mhocko@...nel.org> wrote:
>> 
>> I’m using the function graph tracer to see how long __alloc_pages_nodemask()
>> took.
> 
> How can you map the function graph tracer to a specif context? Let's say
> I would like to know why a particular allocation took so long. Would
> that be possible?

Maybe not. If the latencies are due to direct reclaim or memory compaction, you
get some information from the tracepoints (like mm_vmscan_direct_reclaim_begin,
mm_compaction_begin, etc). But otherwise, you don’t get any context information. 
Function graph only gives the time spent in alloc_pages_nodemask() in that case.


Regards,
Janani.
> 
> -- 
> Michal Hocko
> SUSE Labs