Differential D11942

Have vm_page_grab_pages() support VM_ALLOC_NOWAIT
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Authored by markj on Aug 10 2017, 1:22 AM.

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Reviewers

alc
glebius
kib

Commits

rS322406: Have sendfile_swapin() use vm_page_grab_pages().
rS322405: Modify vm_page_grab_pages() to handle VM_ALLOC_NOWAIT.

Summary

The return value now gives the number of pages (starting at the
requested pindex) returned. This lets sendfile() use vm_page_grab_pages(),
which is marginally more cache-friendly.

Test Plan

I tried this patch with a simple benchmark that uses an AF_UNIX
stream socket pair to simulate a sendfile() to /dev/null. Throughput
goes up by about 1.5% when sending a large (8GB) memory-resident
file.

Edit: I had previous claimed a larger improvement, but had accidentally
been testing with the patch from D11943 applied as well.

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Build Status

Buildable 11012
Build 11398: arc lint + arc unit

Event Timeline

markj created this revision.Aug 10 2017, 1:22 AM

Harbormaster completed remote builds in B10980: Diff 31839.Aug 10 2017, 1:22 AM

markj edited the summary of this revision. (Show Details)Aug 10 2017, 1:30 AM

markj added reviewers: alc, glebius, kib.

alc accepted this revision.Aug 10 2017, 3:49 PM

alc added inline comments.

sys/vm/vm_page.c
3181	I would suggest the phrase "partial prefix". I think it conveys more information.

This revision is now accepted and ready to land.Aug 10 2017, 3:49 PM

alc added a subscriber: brett-gutstein.Aug 10 2017, 6:40 PM

Brett, I added you to this change, because it will decrease the time spent in vm_radix_lookup() by your shm_open()/sendfile() test case.

Clarify the vm_page_grab_pages() comment.

This revision now requires review to proceed.Aug 10 2017, 9:13 PM

Harbormaster completed remote builds in B11012: Diff 31903.Aug 10 2017, 9:13 PM

markj marked an inline comment as done.Aug 10 2017, 9:13 PM

markj edited the test plan for this revision. (Show Details)Aug 11 2017, 5:23 AM

kib accepted this revision.Aug 11 2017, 11:37 AM

This revision is now accepted and ready to land.Aug 11 2017, 11:37 AM

markj edited the test plan for this revision. (Show Details)Aug 11 2017, 3:37 PM

Closed by commit rS322405: Modify vm_page_grab_pages() to handle VM_ALLOC_NOWAIT. (authored by markj). · Explain WhyAug 11 2017, 4:29 PM

This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Path

Size

sys/

kern/

kern_sendfile.c

18 lines

2 lines

sparc64/

sparc64/

2 lines

vm/

4 lines

4 lines

13 lines

Diff 31903

sys/kern/kern_sendfile.c

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sys/kern/vfs_bio.c

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sys/sparc64/sparc64/pmap.c

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sys/vm/vm_glue.c

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sys/vm/vm_page.h

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sys/vm/vm_page.c

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