[LU-11623] Allow caching of open-created dentries

• Type: Improvement
• Resolution: Unresolved
• Priority: Major
• Fix Version/s: Lustre 2.14.0, Lustre 2.12.6, Lustre 2.17.0
• Affects Version/s: Lustre 2.10.0, Lustre 2.11.0
• Assignee: Lai Siyao
• Reporter: Oleg Drokin

Description

Currently when creating/opening a file, we do not let the client hash the name so next access (frequently stat?) goes to talk on the MDS. This is also seen in various tests like mdtest.

We should consider returning more bits from the open call. This is in addition to LU-10948 that handles similar situation for recurring non-creating opens.

Issue Links

• is blocking: LU-17583 Unclean direntry after rename
• is related to: LU-15725 Client side Mdtest File Read Regression introduced with fix for LU-11623
• is related to: LU-10948 client cache open lock after N opens

Comments

[Li Xi]

According to Siyao, this ticket has further issue to fix in LU-17583 thus might be reasonable to defer to 2.17+

[Peter Jones]

Andreas

Does this remain something that we need to address for 2.16?

Peter

[Peter Jones]

Latest patch merged for 2.16. TBH it seems like it would have been better to track this latest work under a new linked Jira than to use this several years old ticket.

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/33585/
Subject: LU-11623 mdt: return UPDATE|PERM on open
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 4b44204930cf4d312425dd95e51720fe5d3e801b

[Shuichi Ihara]

latest patch set (patch set 29) of https://review.whamcloud.com/#/c/fs/lustre-release/+/33585/ patch still demonstrated and promised 9x (86,466 ops vs 789,729 ops) performance boost on open()-create()-stat() workload. And this is same as we are seeing same cached performance on stat()-stat() workload toady. Here is performance comparisons with/without patch.

without patch(commit:8beeec77c3)

mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -C -v -w 32k
mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -T -v -w 32k
SUMMARY rate: (of 1 iterations)
   Operation                      Max            Min           Mean        Std Dev
   ---------                      ---            ---           ----        -------
   File creation             :          0.000          0.000          0.000          0.000
   File stat                 :      86466.293      86466.272      86466.285          0.006
   File read                 :          0.000          0.000          0.000          0.000
   File removal              :          0.000          0.000          0.000          0.000
   Tree creation             :          0.000          0.000          0.000          0.000
   Tree removal              :          0.000          0.000          0.000          0.000

mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -T -v -w 32k
   Operation                      Max            Min           Mean        Std Dev
   ---------                      ---            ---           ----        -------
   File creation             :          0.000          0.000          0.000          0.000
   File stat                 :     779470.812     779428.353     779442.415         18.312
   File read                 :          0.000          0.000          0.000          0.000
   File removal              :          0.000          0.000          0.000          0.000
   Tree creation             :          0.000          0.000          0.000          0.000
   Tree removal              :          0.000          0.000          0.000          0.000

With patch (https://review.whamcloud.com/#/c/fs/lustre-release/+/33585/)

mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -C -v -w 32k
mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -T -v -w 32k
   Operation                      Max            Min           Mean        Std Dev
   ---------                      ---            ---           ----        -------
   File creation             :          0.000          0.000          0.000          0.000
   File stat                 :     789729.392     789726.612     789727.879          0.702
   File read                 :          0.000          0.000          0.000          0.000
   File removal              :          0.000          0.000          0.000          0.000
   Tree creation             :          0.000          0.000          0.000          0.000
   Tree removal              :          0.000          0.000          0.000          0.000
mpirun -np 16 mdtest -n 10000 -d /exafs/d0/d1/d2/ -F -T -v -w 32k
   Operation                      Max            Min           Mean        Std Dev
   ---------                      ---            ---           ----        -------
   File creation             :          0.000          0.000          0.000          0.000
   File stat                 :     790002.623     790000.712     790001.644          0.633
   File read                 :          0.000          0.000          0.000          0.000
   File removal              :          0.000          0.000          0.000          0.000
   Tree creation             :          0.000          0.000          0.000          0.000
   Tree removal              :          0.000          0.000          0.000          0.000

[Gerrit Updater]

"Lai Siyao <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/47163
Subject: LU-11623 mdt: return UPDATE|PERM on open
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 509656f89bd967395da859ea123875ca5db9931c

[Shuichi Ihara]

I would open this ticket since patch https://review.whamcloud.com/#/c/33585 was not merged yet. without this patch, what I showed the performance numbers can't be demonstrated.

[Peter Jones]

Landed for 2.14 and 2.12.6

[Peter Jones]

Do I understand correctly that the work tracked under this ticket landed to 2.13 and 2.12.6?

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/38763/
Subject: LU-11623 llite: hash just created files if lock allows
Project: fs/lustre-release
Branch: b2_12
Current Patch Set:
Commit: 7554658056cddae71fd90ef4a6dd639ddbe3f89b