[LU-9069] ZFS sanity: FAIL: test_255a Speedup with willread is less than XX%, got YY%

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.10.0
• Labels: always_except zfs
• Environment: onyx-64 thru 67; Full Group test, RHEL7.3/ZFS; master branch, b3499
• Severity: 3
• Assignee: WC Triage
• Reporter: James Casper (Inactive)

Description

sanity: FAIL: test_255a Speedup with willread is less than XX%, got YY%

Test is expecting willreads to be faster than cache reads, but willreads are slower:

From test_log:

Iter 1/10: cache speedup: 228%
Iter 1/10: ladvise speedup: 24%

Iter 2/10: cache speedup: 147%
Iter 2/10: ladvise speedup: 20%

Iter 3/10: cache speedup: 170%
Iter 3/10: ladvise speedup: 10%

Related to LU-8565, but that issue was attributed to VM slowness. This issue is also seen on physical machines.

Info required for matching: sanity 255a

Issue Links

• is related to: LU-8565 sanity test 255a fails with ‘Speedup with willread is less than X%, got Y%’
• is related to: LU-6254 Fix OFD/OSD prefetch for osd-ldiskfs and osd-zfs
• is related to: LU-10314 implement ladvise dontneed for ZFS