[LU-11509] LDLM: replace lock LRU with improved cache algorithm Created: 12/Oct/18  Updated: 01/Feb/24

Status: Open
Project: Lustre
Component/s: None
Affects Version/s: None
Fix Version/s: Lustre 2.17.0

Type: Improvement Priority: Major
Reporter: Andreas Dilger Assignee: WC Triage
Resolution: Unresolved Votes: 0
Labels: medium

Issue Links:
Related
is related to LU-14221 Client hangs when using DoM with a fi... Open
is related to LU-6529 Server side lock limits to avoid unne... Closed
is related to LU-7266 Fix LDLM pool to make LRUR working pr... Open
is related to LU-17329 Relaxed POSIX Consistency for Lustre Open
is related to LU-17493 restore LDLM cancel on blocking callback Open
is related to LU-14517 Decrease default lru_max_age value Open
Rank (Obsolete): 9223372036854775807

 Description   

The LDLM LRU algorithm is sub-optimal for managing locks on the client, since it can flush often-used locks when there are a large number of files accessed in a short time (e.g. filesystem scanning). It would be better to implement a more sophisticated cache mechanism, such as ARC, LFRU, or similar (see https://en.wikipedia.org/wiki/Cache_replacement_policies) that includes a frequency count on the lock in addition to only the age of the lock. That will ensure that more important top-level locks are more likely to stay on the client instead of getting flushed.


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