Differential D23847

Convert a few trivial uses to unlocked page lookups.
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Authored by jeff on Feb 27 2020, 3:06 AM.

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alc
dougm
kib
markj

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rS358447: Convert a few triviail consumers to the new unlocked grab API.

Summary

These were all very straightforward. exec/imgact/buf cache all show immediate gain. There are more complex cases coming after this. I have run multiple 48 hour stress2 runs on this and patches later in this series that convert more consumers.

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Repository

rS FreeBSD src repository - subversion

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Event Timeline

jeff created this revision.Feb 27 2020, 3:06 AM

Harbormaster completed remote builds in B29633: Diff 68867.Feb 27 2020, 3:06 AM

jeff edited the summary of this revision. (Show Details)Feb 27 2020, 3:09 AM

jeff added reviewers: alc, dougm, kib, markj.

jeff set the repository for this revision to rS FreeBSD src repository - subversion.

Herald added a subscriber: imp. · View Herald TranscriptFeb 27 2020, 3:09 AM

jeff added inline comments.Feb 27 2020, 3:33 AM

sys/kern/kern_sendfile.c
454 ↗	(On Diff #68867)	We actually could do slightly better here. On return from I/O we don't need the object locked for bogus page replacement. The same is true in the buf cache.

markj added inline comments.Feb 27 2020, 1:51 PM

sys/kern/kern_sendfile.c
364 ↗	(On Diff #68867)	The caller bumps PIP, which is released in sendfile_iodone(). Do we actually need to do that when all of the pages are valid?

jeff added inline comments.Feb 27 2020, 6:35 PM

sys/kern/kern_sendfile.c
364 ↗	(On Diff #68867)	no but it is also harmless and simplified the code.

kib accepted this revision.Feb 28 2020, 1:27 PM

This revision is now accepted and ready to land.Feb 28 2020, 1:27 PM

markj accepted this revision.Feb 28 2020, 3:08 PM

markj added inline comments.

sys/kern/kern_sendfile.c
364 ↗	(On Diff #68867)	It was actually a bit tricky and led to a bug, which is why I asked. r358320 seems to have simplified things a bit though.

Closed by commit rS358447: Convert a few triviail consumers to the new unlocked grab API. (authored by jeff). · Explain WhyFeb 28 2020, 8:34 PM

This revision was automatically updated to reflect the committed changes.

jeff added a commit: rS358447: Convert a few triviail consumers to the new unlocked grab API..

mlaier mentioned this in D26597: Use unlocked page lookup for inmem() to avoid object lock contention.Sep 29 2020, 10:05 PM

Revision Contents
Changeset List

Path

Size

head/

sys/

dev/

drm2/

ttm/

9 lines

md/

4 lines

kern/

10 lines

kern_sendfile.c

12 lines

13 lines

vm/

4 lines

Diff 68971

head/sys/dev/drm2/ttm/ttm_tt.c

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head/sys/dev/md/md.c

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head/sys/kern/kern_exec.c

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head/sys/kern/kern_sendfile.c

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head/sys/kern/vfs_bio.c

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head/sys/vm/vm_glue.c

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