sched:starvation from ubuntu_ltp failed on AWS a1.medium with AWS 5.4 5.15

[Po-Hsu Lin]

After updating our LTP fork to 20240930 [1]

Commit ec14f45 "sched: starvation: Autocallibrate the timeout" is now causing sched:starvation test to fail.

In the commit message:
  We also make sure to check the runtime at the end of the test because
  the failures could have been masked by a timeout multiplier, i.e. if you
  set LTP_TIMEOUT_MUL=10 the test would previously pass on a buggy kernel
  as well. The side efect is that we now get better PASS/FAIL messages as
  well.

This is not a kernel regression, as we did bump the timeout multiplier for bug 2059259.

Test log:
FAILED COMMAND File: /dev/null
TCONF COMMAND File: /dev/null
Running tests.......
tst_tmpdir.c:317: TINFO: Using /tmp/ltp-GGvHDme9Ig/LTP_sta8cBK8W as tmpdir (ext2/ext3/ext4 filesystem)
tst_test.c:1860: TINFO: LTP version: 20230929-874-gba610da01
tst_test.c:1864: TINFO: Tested kernel: 5.4.0-1134-aws #144~18.04.1-Ubuntu SMP Mon Oct 7 13:31:52 UTC 2024 aarch64
tst_test.c:1705: TINFO: Timeout per run is 0h 02m 00s
starvation.c:98: TINFO: Setting affinity to CPU 0
starvation.c:52: TINFO: CPU did 120000000 loops in 104904us
tst_test.c:1712: TINFO: Updating max runtime to 0h 01m 44s
tst_test.c:1705: TINFO: Timeout per run is 0h 03m 44s
starvation.c:148: TFAIL: Scheduller starvation reproduced.

Summary:
passed 0
failed 1
broken 0
skipped 0
warnings 0
INFO: ltp-pan reported some tests FAIL
LTP Version: 20230929-874-gba610da01
INFO: Test end time: Wed Oct 9 12:04:15 UTC 2024

[1] https://lists.ubuntu.com/archives/kernel-team/2024-October/154219.html

[Po-Hsu Lin (cypressyew)]

This is the test result in the previous security cycle (s20240805) on AWS a1.medium, before the LTP fork update. Note the difference for the timeout.

 INFO: Test start time: Tue Sep 10 19:24:14 UTC 2024
 COMMAND: /opt/ltp/bin/ltp-pan -q -e -S -a 11820 -n 11820 -f /tmp/ltp-DK3quVH7Rv/alltests -l /dev/null -C /dev/null -T /dev/null
 LOG File: /dev/null
 FAILED COMMAND File: /dev/null
 TCONF COMMAND File: /dev/null
 Running tests.......
 tst_test.c:1733: TINFO: LTP version: 20230929-609-g3fc2d1b15
 tst_test.c:1619: TINFO: Timeout per run is 0h 02m 00s
 starvation.c:57: TPASS: sched_setaffinity(0, sizeof(mask), &mask) returned 0
 tst_test.c:1626: TINFO: Updating max runtime to 0h 04m 00s
 tst_test.c:1619: TINFO: Timeout per run is 0h 06m 00s
 starvation.c:100: TPASS: wait_for_pid(child_pid) passed

 Summary:
 passed 2
 failed 0
 broken 0
 skipped 0
 warnings 0
 INFO: ltp-pan reported all tests PASS
 LTP Version: 20230929-609-g3fc2d1b15
 INFO: Test end time: Tue Sep 10 19:27:45 UTC 2024