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

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [RFC] scripts: Include postprocessing script for memory allocation tracing
Date	2016-10-06 14:10 +0200
Message-ID	<spfES-8o4-13@gated-at.bofh.it> (permalink)
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On Fri 23-09-16 10:07:09, Michal Hocko wrote:
> On Thu 22-09-16 11:30:36, Janani Ravichandran wrote:
> > 
> > > On Sep 19, 2016, at 5:42 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > > 
> > > On Tue 13-09-16 14:04:49, Janani Ravichandran wrote:
> > >> 
> > >>> On Sep 12, 2016, at 8:16 AM, Michal Hocko <mhocko@kernel.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.
> 
> Then I really think that we need a starting trace point. I think that
> having the full context information is really helpful in order to
> understand latencies induced by allocations.

Are you planning to pursue this path?
-- 
Michal Hocko
SUSE Labs

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Re: [RFC] scripts: Include postprocessing script for memory  allocation tracing Michal Hocko <mhocko@kernel.org> - 2016-10-06 14:10 +0200

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