[LU-14958] configurable hash table size for jbd2

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0, Lustre 2.15.3
• Assignee: Alex Zhuravlev
• Reporter: Alex Zhuravlev

Description

revoke hash table can be enourmous with multi-GB journal. this may result in millions of revoke records which are loaded and inserted into specific hashtable during journal replay.
currently the revoke hashtable's size is hard-coded as 256, thus every slot may get too many records.

a simple benchmark of that code:
1048576 - 95 seconds
2097152 - 580 seconds
in the fields it can be upto 30M records to find/insert.

with 8192 buckets in the hash table:
4194304 - 59 seconds
8388608 - 247 seconds

Issue Links

• is related to: LU-17117 debugfs should be able to disable MMP directly