[LU-12124] slower unlinks with DOM files due to disabled ELC

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Affects Version/s: Lustre 2.12.0
• Severity: 3
• Assignee: Mikhail Pershin
• Reporter: Mikhail Pershin

Description

the problem with slower unlinks was reported by Andrew in LU-11276:

 Subject: LU-11276 ldlm: don't apply ELC to converting and DOM locks

With this patch, unlinkmany (after createmany) performance within a DoM directory drops by ~35%:

HEAD is now at 70a01a6... LU-11276 ldlm: don't apply ELC to converting and DOM locks
total: 20000 unlinks in 52 seconds: 384.615387 unlinks/second
HEAD is now at 7237248... LU-11347 osd: do not use pagecache for I/O
total: 20000 unlinks in 34 seconds: 588.235291 unlinks/second
HEAD is now at 8b9105d... LU-11199 mdt: Attempt lookup lock on open
total: 20000 unlinks in 34 seconds: 588.235291 unlinks/second
HEAD is now at 697e8fe... LU-11473 doc: add lfs-getsom man page
total: 20000 unlinks in 34 seconds: 588.235291 unlinks/second
HEAD is now at ed0c19d... LU-1095 misc: quiet console messages at startup 

That happens due to exclusion of DOM locks from ELC to don't flush data. The possible solution would be lock convert from ELC.

Issue Links

• is related to: LU-12321 Unlink speed needs to be improved in DoM configuration
• is related to: LU-11276 racer: mdc_dev.c:1346:mdc_req_attr_set()) uncovered page