[MDEV-27609] point-select test-case show regression with 4 numa Created: 2022-01-25  Updated: 2022-01-25

Status: Open
Project: MariaDB Server
Component/s: Server
Affects Version/s: 10.8.0
Fix Version/s: None

Type: Bug Priority: Major
Reporter: Krunal Bauskar Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: None


 Description   

1. Start server on 4 numa nodes.
2. TPS as reported by 10.6.6: 942187.16
3. TPS as reported by 10.8: 685072.85
4. Closer look suggested increased contention for MDL rwlock

10.8:

wait/synch/rwlock/sql/MDL_lock::rwlock 2269649.2516 483785033

So per instance wait: 4.69

10.6:

wait/synch/rwlock/sql/MDL_lock::rwlock 883513.5605 658128191

So per instance wait: 1.34

10.8 rw-lock wait is 3.5 times more. Not sure what is causing the increased contention for MDL_lock. Don't see any other mutex contention on InnoDB side or other mutexes.

10.8: 5595ed9d9f20aeb463ac26e075c9cba41927e85e
10.6.6: 21778b8aa88280458f2196aab93044149cf0a18c
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