linux-kernel - Re: [PATCH 4/5] perf arm-spe: Implement find

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Date:   Fri, 15 Oct 2021 22:16:01 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     German Gomez <german.gomez@....com>
Cc:     Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org,
        John Garry <john.garry@...wei.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Mike Leach <mike.leach@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, coresight@...ts.linaro.org,
        James Clark <James.Clark@....com>
Subject: Re: [PATCH 4/5] perf arm-spe: Implement find_snapshot callback

Hi German,

On Fri, Oct 15, 2021 at 01:33:39PM +0100, German Gomez wrote:
> Hi Leo,
> 
> Would you be ok with the current patch the way it is?

Sorry for my failure to catch up the discussion.

As you and Will have mentioned in other emails that it will lead to
breakage if we change to monotonical increasing head, I read the code
and realized the difficulty to use monotonical increasing head in Arm
SPE driver.  So let's use the way as this patch set is.

> In case it's of
> any help, I'm sharing the testing steps that James and I went through
> when testing this internally, if you want to add to it
> 
> - Test that only a portion of the buffer is saved until there is a wraparound
> 
> $ ./perf record -vvv -e arm_spe/period=148576/u -S -- taskset --cpu-list 0 stress --cpu 1 & while true; do sleep 0.2; killall -s USR2 perf; done
> 
> - Test snapshot mode in CPU mode
> 
> $ sudo ./perf record -vvv -C 0 -e arm_spe/period=148576/u -S -- taskset --cpu-list 0 stress --cpu 1 &
> 
> - Test that auxtrace buffers correspond to an aux record
> - Test snapshot default sizes in sudo and user modes
> - Test small snapshot size
> 
> $ ./perf record -vvv -e arm_spe/period=148576/u -S1000 -m16,16 -- taskset --cpu-list 0 stress --cpu 1 &
> 
> If there are any concerns with the patches, please let me know and I
> will try to address them.

Thanks for sharing the testing cases.  Could give me a bit more time for
the test at my side?  And please expect I might give some comments if
I think it's necessary.

Thanks,
Leo