linux-kernel - Re: [PATCH] perf/x86: Unify format of events sysfs show

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Date:   Fri, 25 Mar 2022 09:38:47 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <mingo@...hat.com>, <acme@...nel.org>, <mark.rutland@....com>,
        <alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
        <namhyung@...nel.org>, <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>
Subject: Re: [PATCH] perf/x86: Unify format of events sysfs show

Hi Peter,

On 2022/3/24 18:11, Peter Zijlstra wrote:
> On Thu, Mar 24, 2022 at 11:19:57AM +0800, Yang Jihong wrote:
>> Sysfs show formats of files in /sys/devices/cpu/events/ are not unified,
>> some end with "\n", and some do not. Modify sysfs show format of events
>> defined by EVENT_ATTR_STR to end with "\n".
> 
> Did you test all the userspace that consumes these fields to make sure
> none of them break? I suppose it's mostly perf tool, but I'm fairly sure
> there's others out there as well.
> 
Yes, I tested "perf record" and "perf stat" commands on my machine 
against the modified events, and the results are as follows:

$ perf stat -e 
topdown-fetch-bubbles,topdown-recovery-bubbles,topdown-slots-issued,topdown-slots-retired,topdown-total-slots 
-a sleep 1

  Performance counter stats for 'system wide':

            2356235      topdown-fetch-bubbles     #   1211.9% frontend 
bound
             226132      topdown-recovery-bubbles  #    182.9% bad 
speculation
            1073595      topdown-slots-issued      #  -1780.4% backend bound
             944133      topdown-slots-retired     #    485.6% retiring
             194420      topdown-total-slots

        0.987394388 seconds time elapsed


$ perf record -e 
topdown-fetch-bubbles,topdown-recovery-bubbles,topdown-slots-issued,topdown-slots-retired,topdown-total-slots 
-a sleep 1
Lowering default frequency rate from 4000 to 3000.
Please consider tweaking /proc/sys/kernel/perf_event_max_sample_rate.
Couldn't synthesize bpf events.
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.300 MB perf.data (2620 samples) ]

$ perf evlist
topdown-fetch-bubbles
topdown-recovery-bubbles
topdown-slots-issued
topdown-slots-retired
topdown-total-slots
dummy:HG

.


Thanks,
Jihong
> .
>