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Differential D27942

aio: micro-optimize the lio_opcode assignments
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Authored by asomers on Jan 3 2021, 3:46 PM.
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imp
tmunro

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jhb
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rG2247f4894174: aio: micro-optimize the lio_opcode assignments
Summary

This allows slightly more efficient opcode testing in-kernel. It is
transparent to userland, except to applications that sneakily submit
aio fsync or aio mlock operations via lio_listio, which has never been
documented, requires the use of deliberately undefined constants
(LIO_SYNC and LIO_MLOCK), and is arguably a bug.

Test Plan

existing AIO test suite

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint Passed
Unit
No Test Coverage
Build Status
Buildable 36188
Build 33077: arc lint + arc unit

Event Timeline

asomers created this revision.Jan 3 2021, 3:46 PM
Herald added a subscriber: imp. · View Herald TranscriptJan 3 2021, 3:46 PM
asomers requested review of this revision.Jan 3 2021, 3:46 PM
Harbormaster completed remote builds in B35910: Diff 81584.Jan 3 2021, 3:46 PM
asomers mentioned this in D25071: aio_fsync(O_DSYNC).Jan 6 2021, 3:20 PM
tmunro added a subscriber: tmunro.Jan 7 2021, 9:05 AM
tmunro added a comment.Jan 8 2021, 5:39 AM

Looks OK to me. I suppose we could also use bitmask style for LIO_SYNC and LIO_DATA_ONLY?

jhb added a comment.Jan 8 2021, 9:07 PM

This seems ok to me, though it's not clear if the optimizations really buy anything in perf compared to the (minimal) obfuscation when reading.

I would very much like to see missing validation of opcodes to lio_listio added though, perhaps as a prior commit before this?

asomers updated this revision to Diff 81990.Jan 10 2021, 1:11 AM
  • aio: micro-optimize the lio_opcode assignments
  • Rebase to include LIO_DSYNC
Harbormaster completed remote builds in B36075: Diff 81990.Jan 10 2021, 1:11 AM
asomers added a comment.Jan 10 2021, 1:11 AM

I rebased. I'll open a separate review to validate lio_listio opcodes.

asomers updated this revision to Diff 82244.Jan 14 2021, 4:02 AM
  • aio: micro-optimize the lio_opcode assignments
  • Rebase to include LIO_DSYNC
asomers added a comment.Jan 14 2021, 4:02 AM

Rebased to include lio_listio opcode validation.

Harbormaster completed remote builds in B36188: Diff 82244.Jan 14 2021, 4:02 AM
jhb accepted this revision.Jan 19 2021, 6:53 PM
This revision is now accepted and ready to land.Jan 19 2021, 6:53 PM
Closed by commit rG2247f4894174: aio: micro-optimize the lio_opcode assignments (authored by asomers). · Explain WhyJan 20 2021, 4:03 PM
This revision was automatically updated to reflect the committed changes.
asomers added a commit: rG2247f4894174: aio: micro-optimize the lio_opcode assignments.

Revision Contents
Changeset List

PathSize
sys/
kern/
8 lines
48 lines
sys/
11 lines

Diff 82244

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sys/kern/sys_socket.c

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sys/kern/vfs_aio.c

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sys/sys/aio.h

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