linux-kernel - Re: [PATCH] Add accumulated call counter for memory allocation profiling

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Message-ID: <koa5yyc2opu23giistqjaw3eo47gjcxpx56ekrbsbhltk74wzz@pvym4ollouzu>
Date: Mon, 1 Jul 2024 17:58:50 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: David Wang <00107082@....com>
Cc: Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Add accumulated call counter for memory allocation
 profiling

On Mon, Jul 01, 2024 at 10:23:32AM GMT, David Wang wrote:
> HI Suren, 
> 
> At 2024-07-01 03:33:14, "Suren Baghdasaryan" <surenb@...gle.com> wrote:
> >On Mon, Jun 17, 2024 at 8:33 AM David Wang <00107082@....com> wrote:
> >>
> >> Accumulated call counter can be used to evaluate rate
> >> of memory allocation via delta(counters)/delta(time).
> >> This metrics can help analysis performance behaviours,
> >> e.g. tuning cache size, etc.
> >
> >Sorry for the delay, David.
> >IIUC with this counter you can identify the number of allocations ever
> >made from a specific code location. Could you please clarify the usage
> >a bit more? Is the goal to see which locations are the most active and
> >the rate at which allocations are made there? How will that
> >information be used?
>  
> Cumulative counters can be sampled with timestamp,  say at T1, a monitoring tool got a sample value V1,
> then after sampling interval, at T2,  got a sample value V2. Then the average rate of allocation can be evaluated
> via (V2-V1)/(T2-T1). (The accuracy depends on sampling interval)
> 
> This information "may" help identify where the memory allocation is unnecessary frequent,  
> and  gain some  better performance by making less memory allocation .
> The performance "gain" is just a guess, I do not have a valid example.

Easier to just run perf...