linux-kernel - Re: [PATCH] perf test: Fix perf test case 84 on s390

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Message-ID: <ZxFzb7LEu9n9piVG@google.com>
Date: Thu, 17 Oct 2024 13:28:31 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Thomas Richter <tmricht@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
	acme@...nel.org, agordeev@...ux.ibm.com, gor@...ux.ibm.com,
	sumanthk@...ux.ibm.com, hca@...ux.ibm.com
Subject: Re: [PATCH] perf test: Fix perf test case 84 on s390

Hello,

On Tue, Oct 15, 2024 at 09:47:26AM +0200, Thomas Richter wrote:
> Perf test case 84 'perf pipe recording and injection test'
> sometime fails on s390, especially on z/VM virtual machines.
> 
> This is caused by a very short run time of workload
> 
>   # perf test -w noploop
> 
> which runs for 1 second. Occasionally this is not long
> enough and the perf report has no samples for symbol noploop.
> 
> Fix this and enlarge the runtime for the perf work load
> to 3 seconds. This ensures the symbol noploop is always
> present.

Hmm.. but it would slow down the test quite a lot.  Can you please make
it conditional on s390 or something?

Maybe you could add a fallback logic to increase the period if it fails.

Thanks,
Namhyung

> 
> Output before:
>  Inject -b build-ids test
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.195 MB - ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.277 MB - ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.195 MB - ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.160 MB
> 			 /tmp/perf.data.ELzRdq (4031 samples) ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.195 MB - ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.195 MB - ]
>  Inject -b build-ids test [Success]
> 
>  Inject --buildid-all build-ids test
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.195 MB - ]
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.014 MB - ]
>  Inject --buildid-all build-ids test [Failed - cannot find
> 				noploop function in pipe #2]
> 
> Output after:
> Successful execution for over 10 times in a loop.
> 
> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
> Reviewed-by: Sumanth Korikkar <sumanthk@...ux.ibm.com>
> ---
>  tools/perf/tests/shell/pipe_test.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/pipe_test.sh b/tools/perf/tests/shell/pipe_test.sh
> index d4c8005ce9b9..02d9ef27c8e7 100755
> --- a/tools/perf/tests/shell/pipe_test.sh
> +++ b/tools/perf/tests/shell/pipe_test.sh
> @@ -12,7 +12,7 @@ skip_test_missing_symbol ${sym}
>  
>  data=$(mktemp /tmp/perf.data.XXXXXX)
>  data2=$(mktemp /tmp/perf.data2.XXXXXX)
> -prog="perf test -w noploop"
> +prog="perf test -w noploop 3"
>  err=0
>  
>  set -e
> -- 
> 2.47.0
>