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| author | Leo Yan <leo.yan@arm.com> | 2025-03-31 20:27:59 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2025-05-24 17:40:47 +0300 |
| commit | 628e124404b3db5e10e17228e680a2999018ab33 (patch) | |
| tree | 45ad4b3ad6837ab5570e77da32a044461f04899d /drivers/fpga/fpga-mgr.c | |
| parent | 0ffca606e902151fbe09d4356c493fe79ca93956 (diff) | |
| download | linux-628e124404b3db5e10e17228e680a2999018ab33.tar.xz | |
perf tests switch-tracking: Fix timestamp comparison
The test might fail on the Arm64 platform with the error:
# perf test -vvv "Track with sched_switch"
Missing sched_switch events
#
The issue is caused by incorrect handling of timestamp comparisons. The
comparison result, a signed 64-bit value, was being directly cast to an
int, leading to incorrect sorting for sched events.
The case does not fail everytime, usually I can trigger the failure
after run 20 ~ 30 times:
# while true; do perf test "Track with sched_switch"; done
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : FAILED!
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
106: Track with sched_switch : FAILED!
106: Track with sched_switch : Ok
106: Track with sched_switch : Ok
I used cross compiler to build Perf tool on my host machine and tested on
Debian / Juno board. Generally, I think this issue is not very specific
to GCC versions. As both internal CI and my local env can reproduce the
issue.
My Host Build compiler:
# aarch64-linux-gnu-gcc --version
aarch64-linux-gnu-gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
Juno Board:
# lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 12 (bookworm)
Release: 12
Codename: bookworm
Fix this by explicitly returning 0, 1, or -1 based on whether the result
is zero, positive, or negative.
Fixes: d44bc558297222d9 ("perf tests: Add a test for tracking with sched_switch")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20250331172759.115604-1-leo.yan@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'drivers/fpga/fpga-mgr.c')
0 files changed, 0 insertions, 0 deletions