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From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: like.xu.linux@gmail.com, jmattson@google.com, eranian@google.com,
	santosh.shukla@amd.com, pbonzini@redhat.com, seanjc@google.com,
	wanpengli@tencent.com, vkuznets@redhat.com, joro@8bytes.org,
	mingo@redhat.com, alexander.shishkin@linux.intel.com,
	tglx@linutronix.de, bp@alien8.de, dave.hansen@linux.intel.com,
	hpa@zytor.com, kvm@vger.kernel.org, x86@kernel.org,
	linux-perf-users@vger.kernel.org, ananth.narayan@amd.com,
	kim.phillips@amd.com, Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [PATCH v3] perf/amd: Implement erratum #1292 workaround for F19h M00-0Fh
Date: Thu, 10 Feb 2022 09:35:14 +0530	[thread overview]
Message-ID: <b775ab2d-c293-d8f0-a436-1ec19c6315d8@amd.com> (raw)
In-Reply-To: <YgO4vn2w5kT43HGh@hirez.programming.kicks-ass.net>



On 09-Feb-22 6:21 PM, Peter Zijlstra wrote:
> On Thu, Feb 03, 2022 at 03:28:41PM +0530, Ravi Bangoria wrote:
>> Perf counter may overcount for a list of Retire Based Events. Implement
>> workaround for Zen3 Family 19 Model 00-0F processors as suggested in
>> Revision Guide[1]:
>>
>>   To count the non-FP affected PMC events correctly:
>>     o Use Core::X86::Msr::PERF_CTL2 to count the events, and
>>     o Program Core::X86::Msr::PERF_CTL2[43] to 1b, and
>>     o Program Core::X86::Msr::PERF_CTL2[20] to 0b.
>>
>> Note that the specified workaround applies only to counting events and
>> not to sampling events. Thus sampling event will continue functioning
>> as is.
>>
>> Although the issue exists on all previous Zen revisions, the workaround
>> is different and thus not included in this patch.
>>
>> This patch needs Like's patch[2] to make it work on kvm guest.
>>
>> [1] https://bugzilla.kernel.org/attachment.cgi?id=298241
>> [2] https://lore.kernel.org/lkml/20220117055703.52020-1-likexu@tencent.com
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
> 
> Thanks!

Peter, On subsequent tests, I found that this 'fix' is still not
optimal. Please drop this patch from your queue for now. Really
sorry for the noise.

Thanks,
Ravi

  reply	other threads:[~2022-02-10  4:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-17  5:57 [PATCH] KVM: x86/pmu: Clear reserved bit PERF_CTL2[43] for AMD erratum 1292 Like Xu
2022-02-02  4:28 ` [PATCH] perf/amd: Implement errata #1292 workaround for F19h M00-0Fh Ravi Bangoria
2022-02-02  5:27   ` Stephane Eranian
2022-02-02  6:02     ` Ravi Bangoria
2022-02-02  6:16       ` Stephane Eranian
2022-02-02  6:32         ` Ravi Bangoria
2022-02-02 10:51           ` [PATCH v2] perf/amd: Implement erratum " Ravi Bangoria
2022-02-02 14:36             ` Peter Zijlstra
2022-02-02 15:32               ` Ravi Bangoria
2022-02-03  9:58                 ` [PATCH v3] " Ravi Bangoria
2022-02-09 12:51                   ` Peter Zijlstra
2022-02-10  4:05                     ` Ravi Bangoria [this message]
2022-02-10  8:46                       ` Peter Zijlstra
2022-02-03  4:09             ` [PATCH v2] " Jim Mattson
2022-02-03  5:18               ` Ravi Bangoria
2022-02-03 17:55                 ` Jim Mattson
2022-02-04  9:32                   ` Ravi Bangoria
2022-02-04 13:01                     ` Jim Mattson
2022-02-09 10:18                       ` Like Xu
2022-02-09 21:40                         ` Jim Mattson
2022-02-10  4:06                           ` Ravi Bangoria
2022-02-10 13:56                             ` Like Xu

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