On s390 using linux-next the test case:
87: perf record offcpu profiling tests
fails. The root cause is this command
# ./perf record --off-cpu -e dummy -- ./perf bench sched messaging -l 10
# Running 'sched/messaging' benchmark:
# 20 sender and receiver processes per group
# 10 groups == 400 processes run
Total time: 0.231 [sec]
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.077 MB perf.data (401 samples) ]
#
It does not generate 800+ sample entries, on s390 usually around
40[1-9], sometimes a few more, but never more than 450. The higher the
number of CPUs the lower the number of samples.
Looking at function chain:
bench_sched_messaging()
+--> group()
the senders and receiver threads are created. The senders and receivers
call function ready() which writes one bytes and wait for a reply using
poll system() call.
As context switches are counted, the function ready() will trigger a
context switch when no input data is available after the write system
call. The write system call does not trigger context switches when the
data size is small. And writing 1000 bytes (10 iterations with
100 bytes) is not much and certainly won't block.
The 400+ context switch on s390 occur when the some receiver/sender
threads call ready() and wait for the response from function
bench_sched_messaging() being kicked off.
Lower the number of expected context switches to 400 to succeed on s390.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Co-developed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20231106091627.2022530-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Running shellcheck on record_offcpu.sh throws below warning:
In tests/shell/record_offcpu.sh line 13:
trap - exit term int
^--^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
^--^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
^-^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
In tests/shell/record_offcpu.sh line 20:
trap trap_cleanup exit term int
^--^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
^--^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
^-^ SC3049 (warning): In POSIX sh, using lower/mixed case for signal names is undefined.
In tests/shell/record_offcpu.sh line 25:
if [ `id -u` != 0 ]
^-----^ SC2046 (warning): Quote this to prevent word splitting.
Fixed the warnings by:
- Capitalize signals(INT, TERM, EXIT) to avoid mixed/lower case naming of
signals.
- Adding quotes to avoid word splitting.
Result from shellcheck after patch changes:
$ shellcheck -S warning record_offcpu.sh
$
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230709182800.53002-4-atrajeev@linux.vnet.ibm.com
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This reverts commit a980755beb.
We need to better polish building with BPF skels, so revert back to
making it an experimental feature that has to be explicitely enabled
using BUILD_BPF_SKEL=1.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
