linux-kernel - Re: [PATCH] perf test: Increase buffer size for Coresight basic tests

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Message-ID: <Zh_1pR9nK1d-bivl@x1>
Date: Wed, 17 Apr 2024 13:15:33 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: James Clark <james.clark@....com>, linux-perf-users@...r.kernel.org,
	Mike Leach <mike.leach@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf test: Increase buffer size for Coresight basic tests

On Mon, Apr 15, 2024 at 01:55:25PM +0530, Anshuman Khandual wrote:
> 
> 
> On 4/12/24 13:52, James Clark wrote:
> > 
> > 
> > On 12/04/2024 08:04, Anshuman Khandual wrote:
> >>
> >>
> >> On 3/26/24 17:07, James Clark wrote:
> >>> These tests record in a mode that includes kernel trace but look for
> >>> samples of a userspace process. This makes them sensitive to any kernel
> >>> compilation options that increase the amount of time spent in the
> >>> kernel. If the trace buffer is completely filled before userspace is
> >>> reached then the test will fail. Double the buffer size to fix this.
> >>
> >> This is a valid concern to address, but just wondering how did we arrive
> >> at the conclusion that doubling the buffer size i.e making that 8M will
> >> solve the problem positively for vast number of kerne build scenarios ?
> >>
> > 
> > Nobody else has reported anything yet, if it happens again we can always
> > increase it again if that is what the issue is. I had most of the kernel
> > debugging stuff turned on like memory debugging etc, which is probably
> > why I ran into it and 8MB fixed it for me. So I'm not sure if there is
> > much more that could be added.
> 
> Makes sense,
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>

Thanks, applied to perf-tools-next,

- Arnaldo