[LU-1757] Short I/O support

• Type: Improvement
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.11.0, Lustre 2.12.0
• Labels: patch
• Assignee: Patrick Farrell (Inactive)
• Reporter: Alexander Boyko

Description

Perform short I/O (requests <= 4k) w/o bulk RPC.

Issue Links

• is related to: LU-12856 LustreError: 82937:0:(ldlm_lib.c:3268:target_bulk_io()) @@@ truncated bulk READ 0(270336)
• is related to: LU-10264 New static analysis issues in v2_10_55_0-30-g3cbe63e
• is related to: LU-10289 DoM: add SHORTIO support for MDS RPCs
• is related to: LU-9409 Lustre small IO write performance improvement
• is related to: LU-10176 Data-on-MDT phase II
• is related to: LU-3285 Data on MDT

Comments

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/33173/
Subject: LU-1757 osc: clarify short_io_bytes is maximum value
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: b90812a674f6ebaa9de592a4a4d97a35ed38a24e

[Gerrit Updater]

Andreas Dilger ([e-mail]) uploaded a new patch: https://review.whamcloud.com/33173
Subject: LU-1757 osc: clarify short_io_bytes is maximum value
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 8e3e67f0cfdec0bb0a96f9e4fc1793fef7558867

[Peter Jones]

Second time lucky?

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/30435/
Subject: LU-1757 brw: Fix short i/o and enable for mdc
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 3483e195314bddb8d72594ebb10307c83a4bb860

[Patrick Farrell (Inactive)]

Original patch did not actually enable this functionality.

[Gerrit Updater]

Patrick Farrell ([e-mail]) uploaded a new patch: https://review.whamcloud.com/30435
Subject: LU-1757 brw: Fix short i/o and enable for mdc
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 8efc38861cb224d69c012862f6e8ae453b890d17

[Andreas Dilger]

This was landed for 2.11, but Data-on-MDT landed at the same time. The MDS connection does not support SHORTIO yet, but it should.

[Minh Diep]

Landed for 2.11

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/27767/
Subject: LU-1757 brw: add short io osc/ost transfer.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 70f092a0587866662735e1a6eaf27701a576370d

[Patrick Farrell (Inactive)]

Andreas,

Aligned, mostly. Can't really test unaligned without getting aggregation or readahead, except for random reads. (Those do well.)

Server side locking... How is that achieved, other than with the patch from LU-4198, and that only for direct i/o? (https://review.whamcloud.com/#/c/8201/20)
And since it's direct i/o, it has to be aligned. (Trying to update LU-247 (unaligned dio) is my next project.)

Also, other than with direct i/o, I'm not sure how to actually achieve small i/os (write aggregation or read ahead will prevent them), except for random reads. (Which do see a benefit - I didn't mention that, but they see the same sort of improvement.)

So, I suppose I would say:
I want to try all of that, I agree that it would likely benefit enormously (you pointed this out in your earlier comments to this LU) but I believe I need LU-247 to make it really possible, since direct i/o is the only way I know of to A) skip the page cache, B) force small i/o, and C) move the locking to the server (I can fake the effect of that by doing my i/o from one node.)

Is there some easier route I've missed?