[LU-13386] allow over reservation to cover current read

• Status: Resolved
• Project: Lustre
• Fix Version/s: Lustre 2.14.0
• Type: Bug
• Priority: Minor
• Reporter: Wang Shilong (Inactive)
• Assignee: Wang Shilong (Inactive)
• Resolution: Fixed
• Severity: 3

Description

ll_ra_count_get() is designed to allow over reservation for performance reasons, this could happen that multiple threads consuming a small readahead window limit, it will fallback to small 4K read which hurts performances.

Issue Links

• is related to: LU-12043 improve Lustre single thread read per...

Comments

[Gerrit Updater]

Wang Shilong ([e-mail]) uploaded a new patch: https://review.whamcloud.com/38047
Subject: LU-13386 readahead: fix to allow over reservation to cover current read
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: f67bfe62dbd91b965ca59a8978eafdbc84c71c6f

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/38047/
Subject: LU-13386 llite: allow current readahead to exceed reservation
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 777b04a09356afe425e9dc3dd3de385109990b52

[Nathan Dauchy (Inactive)]

Please also backport to b2_12.  Thanks!

[Peter Jones]

Don't worry dauchy we do have a process to track this kind of thing (though admittedly it usually takes longer than 30 mins )

[Wang Shilong (Inactive)]

I checked that b2_12 did not backport:

LU-12043 llite: make sure readahead cover current read

So we don't need the patch to b2_12 branch unless above patch ported to b2_12 firstly.