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Differential D40807

radix_trie: avoid code duplication in insert
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Authored by dougm on Jun 30 2023, 7:20 AM.
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pho

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alc
markj
kib
Commits
rG16e01c05c09e: radix_trie: avoid code duplication in insert
Summary

Two cases in the insert routine are written differently, when they're really doing the same thing. Writing that case only once saves 208 bytes in the compiled vm_radix_insert code.

Test Plan

I have successfully booted a kernel with it.

A pair of 'make buildworld' tests counted function calls and cycles spent on vm_radix_insert.

old
vm.radix.ins_cycles: 80079998931
vm.radix.ins_calls: 344880306
cycles/call: 232.19649698118744

new
vm.radix.ins_cycles: 78438877181
vm.radix.ins_calls: 344817853
cycles/call: 227.47916472004715

Peter, can you test this please?

Diff Detail

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rG FreeBSD src repository
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Event Timeline

dougm requested review of this revision.Jun 30 2023, 7:20 AM
dougm created this revision.
dougm added inline comments.Jun 30 2023, 9:48 PM
sys/kern/subr_pctrie.c
406

After this change, both pctrie_keydiff and pctrie_node_get are invoked only once.
They could just be eliminated and inlined here.

dougm added a reviewer: kib.Jul 1 2023, 11:17 PM
dougm updated this revision to Diff 124291.Jul 7 2023, 4:41 PM
dougm edited the summary of this revision. (Show Details)

Update after introducing popmaps.

dougm edited the test plan for this revision. (Show Details)Jul 7 2023, 7:00 PM
dougm updated this revision to Diff 124308.Jul 7 2023, 7:20 PM

Restore some lines changed to avoid long lines.

dougm edited the test plan for this revision. (Show Details)Jul 7 2023, 7:20 PM
dougm edited the test plan for this revision. (Show Details)
dougm added a subscriber: pho.
pho added a comment.Jul 9 2023, 5:50 AM

I ran test with D40807.id124308.diff for 15 hours without seeing any issues. This on:

FreeBSD mercat1.netperf.freebsd.org 14.0-CURRENT FreeBSD 14.0-CURRENT #0 main-n264058-5fee12e18967d-dirty: Sat Jul  8 16:35:55 CEST 2023     pho@mercat1.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO amd64
dougm updated this revision to Diff 124412.Jul 9 2023, 6:44 PM

Improve comments. Adhere to line-wrap style.

alc accepted this revision.Jul 9 2023, 8:00 PM
This revision is now accepted and ready to land.Jul 9 2023, 8:00 PM
Closed by commit rG16e01c05c09e: radix_trie: avoid code duplication in insert (authored by dougm). · Explain WhyJul 9 2023, 8:07 PM
This revision was automatically updated to reflect the committed changes.
dougm added a commit: rG16e01c05c09e: radix_trie: avoid code duplication in insert.
Herald added a subscriber: imp. · View Herald TranscriptJul 9 2023, 8:07 PM

Revision Contents
Changeset List

PathSize
sys/
kern/
51 lines
vm/
50 lines

Diff 124416

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sys/kern/subr_pctrie.c

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sys/vm/vm_radix.c

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