[LU-12368] concurrent statfs() calls on the client should be blocked

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.13.0
• Affects Version/s: Lustre 2.10.8, Lustre 2.12.3
• Labels: easy
• Assignee: Andreas Dilger
• Reporter: Andreas Dilger

Description

If multiple threads on a client are executing statfs() calls concurrently, and the obd_statfs() cache has expired, then each thread will send an OST_STATFS RPC to each OST. With certain statfs-heavy workloads on many-core client nodes, this can result in thousands of needless RPCs being sent from each client every few seconds.

Since all of the callers funnel through obd_statfs(), and there is no benefit to having multiple OST_STATFS or MDS_STATFS replies from the same target (they return the same data, and all threads are blocked on the reply) it makes sense to just allow one thread to execute the statfs and other threads to (interruptibly) wait for it to complete.

Issue Links

• is related to: LU-13296 statfs isn't work properly with MDT statfs proxy

Comments

[Alexey Lyashkov]

In fact - fix is incorrect. Lets look to LU-13296.

[Gerrit Updater]

Minh Diep ([e-mail]) uploaded a new patch: https://review.whamcloud.com/36874
Subject: LU-12368 ptlrpc: make DEBUG_REQ messages consistent
Project: fs/lustre-release
Branch: b2_12
Current Patch Set: 1
Commit: bcf0777c27333aade617e92b9cfe03877e568e4e

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/35311/
Subject: LU-12368 ptlrpc: make DEBUG_REQ messages consistent
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: c0fa0ba4a8efcd774f1fe27986a0217c76dedf6d

[Andreas Dilger]

Patrick, there is still patch https://review.whamcloud.com/35383 "obdclass: allow 'lfs df' to specify cache age" still open. I added that patch while working on "obdclass: don't send multiple statfs RPCs" but I'm not sure if it is actually useful to land or not.

[Patrick Farrell (Inactive)]

Andreas,

Any reason this ticket is still open?  I think we've got the patches all merged.

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/35485/
Subject: LU-12368 obdclass: don't send multiple statfs RPCs
Project: fs/lustre-release
Branch: b2_12
Current Patch Set:
Commit: 1839debbba0e70dd5cc9f11c8bc83bcead0114d4