clock_gettime04 from ubuntu_ltp_syscalls failed with "Difference between successive readings greater than 5 ms" on trusty/linux-azure

[Kleber Sacilotto de Souza]

Found with trusty/linux-azure 4.15.0-1114.127~14.04.1.

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startup='Sat Apr 24 20:55:04 2021'
tst_test.c:1250: TINFO: Timeout per run is 0h 05m 00s
sh: 1: systemd-detect-virt: not found
vdso_helpers.c:76: TINFO: Couldn't find vdso_gettime64()
clock_gettime04.c:151: TFAIL: CLOCK_REALTIME: Difference between successive readings greater than 5 ms (2): 5
clock_gettime04.c:151: TFAIL: CLOCK_REALTIME_COARSE: Difference between successive readings greater than 5 ms (2): 8
clock_gettime04.c:151: TFAIL: CLOCK_MONOTONIC: Difference between successive readings greater than 5 ms (2): 6
clock_gettime04.c:151: TFAIL: CLOCK_MONOTONIC_COARSE: Difference between successive readings greater than 5 ms (2): 12
clock_gettime04.c:151: TFAIL: CLOCK_MONOTONIC_RAW: Difference between successive readings greater than 5 ms (2): 6
clock_gettime04.c:151: TFAIL: CLOCK_BOOTTIME: Difference between successive readings greater than 5 ms (1): 6

Summary:
passed 0
failed 6
skipped 0
warnings 0
tag=clock_gettime04 stime=1619297704 dur=0 exit=exited stat=1 core=no cu=5 cs=2
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This is not a regression as it has been failing on previous releases as well.

[Guilherme G. Piccoli (gpiccoli)]

Found on T-4.15/Azure, cycle sru-20210531 - as per Kleber's comment, not a regression per se.

[Po-Hsu Lin (cypressyew)]

This is failing on Trusty because we use systemd to control the time-sync, which is not exist on Trusty.
Found on T-azure 4.15.0-1124.137~14.04.1

[Po-Hsu Lin (cypressyew)]

BTW it seems this is only happening on Standard_A2_v2

[Krzysztof Kozlowski (krzk)]

Similar to lp:1892181.

Found also on 2022.01.03/trusty/linux-azure/4.15.0-1130.143~14.04.1 (instance Standard_B1ms), only one failure:
clock_gettime04.c:163: TFAIL: CLOCK_MONOTONIC_COARSE(vDSO with old kernel spec): Difference between successive readings greater than 5 ms (2): 7