[LTP] [PATCH v2] sched: starvation: Autocallibrate the timeout

[joe.liu]

Hi Cyril,

> Instead of hardcoding the values we attempt to measure the CPU speed and
> set the timeout accordingly. Given that the difference in the duration
> of the test when the kernel is buggy is about 30x we do not have to have
> a precise callibration, just very rough estimate if we are running on a
> server or small ARM board would suffice.

> So we attempt to measure how long does a bussy loop take and base the
> default timeout on that. On x86_64 CPUs the resulting timeout is about
> double of the value of the actual test runtime and works fine, but we
> need to make sure that the coeficient we divide the result from
> callibrate works for small boards too. So please run the test on as many
> machines as you can and report if we need to make the dividor smaller or
> not.

While applying this new patch, the test result of 32bit kernel is still failed. Please refers following log:

external/ltp/lib/tst_test.c:1690: TINFO: LTP version: 20230929
external/ltp/lib/tst_test.c:1576: TINFO: Timeout per run is 0h 00m 30s
external/ltp/testcases/kernel/sched/cfs-scheduler/starvation.c:90: TPASS: sched_setaffinity(0, sizeof(mask), &mask) returned 0
external/ltp/testcases/kernel/sched/cfs-scheduler/starvation.c:58: TINFO: CPU did 100000000 loops in 198306us
external/ltp/testcases/kernel/sched/cfs-scheduler/starvation.c:99: TINFO: cal timeout: 198
external/ltp/lib/tst_test.c:1583: TINFO: Updating max runtime to 0h 03m 18s
external/ltp/lib/tst_test.c:1576: TINFO: Timeout per run is 0h 03m 48s
Test timeouted, sending SIGKILL!

After using "time ./starvation" to check the timecost, we can see the timecost is about 26 mins and 48 seconds