linux-kernel - Re: [PATCH v3 08/10] perf/core: Introduce pmu->adjust

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Message-ID: <586512b3-661d-4cdf-912f-fcd53c095896@amd.com>
Date: Wed, 8 Jan 2025 16:46:42 +0530
From: Ravi Bangoria <ravi.bangoria@....com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: mingo@...hat.com, namhyung@...nel.org, acme@...nel.org,
 eranian@...gle.com, mark.rutland@....com,
 alexander.shishkin@...ux.intel.com, jolsa@...nel.org, irogers@...gle.com,
 adrian.hunter@...el.com, kan.liang@...ux.intel.com, tglx@...utronix.de,
 bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 santosh.shukla@....com, ananth.narayan@....com, sandipan.das@....com,
 Ravi Bangoria <ravi.bangoria@....com>
Subject: Re: [PATCH v3 08/10] perf/core: Introduce pmu->adjust_period()
 callback

On 18-Dec-24 7:22 PM, Peter Zijlstra wrote:
> On Tue, Dec 10, 2024 at 09:34:47AM +0000, Ravi Bangoria wrote:
>> Many hardware PMUs have constraints about sample period. For ex, minimum
>> supported sample period for IBS Op PMU is 0x90, the sample period must
>> be multiple of 0x10 for IBS Fetch and IBS Op.
>>
>> Add an optional callback adjust_period() to struct PMU to allow PMU
>> specific drivers to adjust sample period calculated by generic code.
>> This will ensure the sample_period value will always be valid and no
>> additional code is required in PMU specific drivers to re-adjust the
>> period.
> 
> And not a word about pmu::check_period() and x86_pmu::limit_period() :-(

Let me collate them. Will respin.

Thanks for the feedback,
Ravi