linux-kernel - Re: [PATCH] perf test: Fix test_arm

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Message-ID: <Yz7qx+4BxNYOCgvL@leoy-yangtze.lan>
Date:   Thu, 6 Oct 2022 22:48:39 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     James Clark <james.clark@....com>
Cc:     coresight@...ts.linaro.org, acme@...nel.org,
        suzuki.poulose@....com, linux-perf-users@...r.kernel.org,
        mathieu.poirier@...aro.org, mike.leach@...aro.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf test: Fix test_arm_coresight.sh failures on Juno

Hi James,

On Wed, Oct 05, 2022 at 03:05:08PM +0100, James Clark wrote:
> This test commonly fails on Arm Juno because the instruction interval
> is large enough to miss generating any samples for Perf in system-wide
> mode.
>
> Fix this by lowering the interval until a comfortable number of Perf
> instructions are generated. The test is still quick to run because only
> a small amount of trace is gathered.
> 
> Before:
> 
>   sudo ./perf test coresight -vvv
>   ...
>   Recording trace with system wide mode
>   Looking at perf.data file for dumping branch samples:
>   Looking at perf.data file for reporting branch samples:
>   Looking at perf.data file for instruction samples:
>   CoreSight system wide testing: FAIL
>   ...
> 
> After:
> 
>   sudo ./perf test coresight -vvv
>   ...
>   Recording trace with system wide mode
>   Looking at perf.data file for dumping branch samples:
>   Looking at perf.data file for reporting branch samples:
>   Looking at perf.data file for instruction samples:
>   CoreSight system wide testing: PASS
>   ...

Since Arm Juno board has zero timestamp for CoreSight, I don't think
now arm_cs_etm.sh can really work on it.

If we want to pass the test on Juno board, we need to add option
"--itrace=Zi1000i" for "perf report" and "perf script"; but seems
to me "--itrace=Z..." is not a general case for testing ...

> Signed-off-by: James Clark <james.clark@....com>
> ---
>  tools/perf/tests/shell/test_arm_coresight.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/test_arm_coresight.sh b/tools/perf/tests/shell/test_arm_coresight.sh
> index e4cb4f1806ff..daad786cf48d 100755
> --- a/tools/perf/tests/shell/test_arm_coresight.sh
> +++ b/tools/perf/tests/shell/test_arm_coresight.sh
> @@ -70,7 +70,7 @@ perf_report_instruction_samples() {
>  	#   68.12%  touch    libc-2.27.so   [.] _dl_addr
>  	#    5.80%  touch    libc-2.27.so   [.] getenv
>  	#    4.35%  touch    ld-2.27.so     [.] _dl_fixup
> -	perf report --itrace=i1000i --stdio -i ${perfdata} 2>&1 | \
> +	perf report --itrace=i20i --stdio -i ${perfdata} 2>&1 | \
>  		egrep " +[0-9]+\.[0-9]+% +$1" > /dev/null 2>&1

So here I am suspect that changing to "--itrace=i20i" can allow the test
to pass on Juno board.  Could you confirm for this?

Thanks,
Leo