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From: German Gomez <german.gomez@arm.com>
To: James Clark <james.clark@arm.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Cc: Chase Conklin <chase.conklin@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Ian Rogers <irogers@google.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Stephane Eranian <eranian@google.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	"acme@kernel.org" <acme@kernel.org>
Subject: Re: [PATCH] perf record/arm-spe: Override attr->sample_period for non-libpfm4 events
Date: Mon, 17 Jan 2022 10:27:11 +0000	[thread overview]
Message-ID: <35a4f70f-d7ef-6e3c-dc79-aa09d87f0271@arm.com> (raw)
In-Reply-To: <c2b960eb-a25e-7ce7-ee4b-2be557d8a213@arm.com>

Hi James,

On 17/01/2022 09:59, James Clark wrote:
>
> On 14/01/2022 21:21, German Gomez wrote:
>> A previous commit preventing attr->sample_period values from being
>> overridden in pfm events changed a related behaviour in arm_spe.
>>
>> Before this patch:
>> perf record -c 10000 -e arm_spe_0// -- sleep 1
>>
>> Would not yield an SPE event with period=10000, because the arm-spe code
> Just to clarify, this seems like it should say "Would yield", not "Would not yield",
> as in it was previously working?

"this patch" refers to the patch I'm sending, not the one it's fixing.
I might have to rewrite this to make it more clear. How about:

===
A previous patch preventing "attr->sample_period" values from being
overridden in pfm events changed a related behaviour in arm-spe.

Before said patch:
perf record -c 10000 -e arm_spe_0// -- sleep 1

Would yield an SPE event with period=10000. After the patch, the period
in "-c 10000" was being ignored because the arm-spe code initializes
sample_period to a non-zero value.

This patch restores the previous behaviour for non-libpfm4 events.
===

Thanks for the review,
German

  reply	other threads:[~2022-01-17 10:27 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-14 21:21 [PATCH] perf record/arm-spe: Override attr->sample_period for non-libpfm4 events German Gomez
2022-01-17  9:59 ` James Clark
2022-01-17 10:27   ` German Gomez [this message]
2022-01-17 16:28     ` Ian Rogers
2022-01-17 21:32       ` German Gomez
2022-01-18 12:32         ` Arnaldo Carvalho de Melo
2022-01-22 20:15           ` Arnaldo Carvalho de Melo
2022-01-22 20:17       ` Arnaldo Carvalho de Melo

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