linux-kernel - Re: [PATCH V2] perf test: Fix test perf stat tests for virtualized machines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <eca46457-0e1a-43b8-b6ac-bd61a7a273f1@linaro.org>
Date: Wed, 7 Jan 2026 15:30:43 +0000
From: James Clark <james.clark@...aro.org>
To: Thomas Richter <tmricht@...ux.ibm.com>
Cc: agordeev@...ux.ibm.com, gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
 hca@...ux.ibm.com, japo@...ux.ibm.com, linux-kernel@...r.kernel.org,
 linux-s390@...r.kernel.org, linux-perf-users@...r.kernel.org,
 acme@...nel.org, namhyung@...nel.org, irogers@...gle.com
Subject: Re: [PATCH V2] perf test: Fix test perf stat tests for virtualized
 machines



On 07/01/2026 1:32 pm, Thomas Richter wrote:
> V1 --> V2: Add correct Fixes: tag, suggested by James Clark
> 
> On s390 perf test 'perf stat tests', subtest test_hybrid fails
> for z/VM systems.
> The root cause is this statement:
> 
>    $(perf stat -a -- sleep 0.1 2>&1 |\
>                    grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]* -c)
> 
> The perf stat output on a s390 z/VM system is
> 
>   # perf stat -a -- sleep 0.1 2>&1
>   Performance counter stats for 'system wide':
> 
>         56      context-switches  #     46.3 cs/sec  cs_per_second
>   1,210.41 msec cpu-clock         #     11.9 CPUs  CPUs_utilized
>         12      cpu-migrations    #      9.9 migrations/sec ...
>         81      page-faults       #     66.9 faults/sec ...
> 
>         0.100891009 seconds time elapsed
> 
> The grep command does not match any single line and exits with error
> code 1. As the bash script is executed with set -e, it aborts with the
> first error code being non-zero.
> 
> Fix this and use wc -l to count matching lines instead of grep ... -c.
> 
> Output before:
>   # perf test 102
>   102: perf stat tests                      : FAILED!
>   #
> Output after:
>   # perf test 102
>   102: perf stat tests                      : Ok
>   #
> 
> Fixes: bb6e7cb11d97c ("perf tools: Add fallback for exclude_guest")
> Cc: James Clark <james.clark@...aro.org>
> Cc: Ian Rogers <irogers@...gle.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
> ---
>   tools/perf/tests/shell/stat.sh | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/stat.sh b/tools/perf/tests/shell/stat.sh
> index 0b2f0f88ca16..792a0b79f6b8 100755
> --- a/tools/perf/tests/shell/stat.sh
> +++ b/tools/perf/tests/shell/stat.sh
> @@ -233,7 +233,7 @@ test_hybrid() {
>     fi
>   
>     # Run default Perf stat
> -  cycles_events=$(perf stat -a -- sleep 0.1 2>&1 | grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]*  " -c)
> +  cycles_events=$(perf stat -a -- sleep 0.1 2>&1 | grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]*  "  | wc -l)
>   
>     # The expectation is that default output will have a cycles events on each
>     # hybrid PMU. In situations with no cycles PMU events, like virtualized, this

Reviewed-by: James Clark <james.clark@...aro.org>