linux-kernel - Re: [PATCH] perf/x86/intel/uncore: Fix client IMC events return huge result

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Message-ID: <20181116161235.GF1706@sasha-vm>
Date:   Fri, 16 Nov 2018 11:12:35 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     kan.liang@...ux.intel.com
Cc:     tglx@...utronix.de, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        yao.jin@...ux.intel.com, stable@...r.kernel.org
Subject: Re: [PATCH] perf/x86/intel/uncore: Fix client IMC events return huge
 result

On Fri, Nov 16, 2018 at 05:19:45AM -0800, kan.liang@...ux.intel.com wrote:
>From: Kan Liang <kan.liang@...ux.intel.com>
>
>The client IMC bandwidth events return very huge result.
>  perf stat -e uncore_imc/data_reads/ -e uncore_imc/data_writes/ -I
>10000 -a
>  10.000117222 34,788.76 MiB uncore_imc/data_reads/
>  10.000117222 8.26 MiB uncore_imc/data_writes/
>  20.000374584 34,842.89 MiB uncore_imc/data_reads/
>  20.000374584 10.45 MiB uncore_imc/data_writes/
>  30.000633299 37,965.29 MiB uncore_imc/data_reads/
>  30.000633299 323.62 MiB uncore_imc/data_writes/
>  40.000891548 41,012.88 MiB uncore_imc/data_reads/
>  40.000891548 6.98 MiB uncore_imc/data_writes/
>  50.001142480 1,125,899,906,621,494.75 MiB uncore_imc/data_reads/
>  50.001142480 6.97 MiB uncore_imc/data_writes/
>
>The client IMC events are freerunning counters. They still use the
>old event encoding format (0x1 for data_read and 0x2 for data write).
>The counter bit width is calculated by common code, which assume that
>the standard encoding format is used for the freerunning counters.
>Error bit width information is calculated.
>
>The event->attr.config, which directly from user space, should not be
>used by the functions of freerunning counters.
>For client IMC events, the attr.config needs to be converted to the
>standard encoding format. The modified event config will be stored in
>event->hw.config.
>For other freerunning counters, the attr.config has the correct format.
>Just save it in event->hw.config.
>Using event->hw.config to replace event->attr.config for the functions
>of freerunning counters.
>
>Fix: commit 9aae1780e7e8 ("perf/x86/intel/uncore: Clean up client IMC
>uncore")

Please use a "fixes" (vs "fix") tag here, a few folks have automation
around this. It should look something like this:

	Fixes: commit 9aae1780e7e8 ("perf/x86/intel/uncore: Clean up client IMC uncore")

Also, if you intend for this to go in stable trees, please add a stable
tag rather than just cc it to the stable mailing list. Something like
this:

	Cc: stable@...nel.org

--
Thanks,
Sasha