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Date: Wed, 17 Apr 2024 13:15:33 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: James Clark <james.clark@arm.com>, linux-perf-users@vger.kernel.org,
	Mike Leach <mike.leach@linaro.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>, coresight@lists.linaro.org,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf test: Increase buffer size for Coresight basic tests
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References: <20240326113749.257250-1-james.clark@arm.com>
 <5a4023aa-af9b-48d2-84f3-a0b9b30dc54e@arm.com>
 <7f5c32dd-edc6-4b53-9cdd-780756f5536c@arm.com>
 <369b29bf-66d8-4876-ae0c-a35f3c46973e@arm.com>
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In-Reply-To: <369b29bf-66d8-4876-ae0c-a35f3c46973e@arm.com>

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@arm.com>

Thanks, applied to perf-tools-next,

- Arnaldo