subr_pctrie: use ilog2(x) instead of fls(x)-1
ClosedPublic
Actions

Authored by dougm on May 24 2024, 5:01 AM.

Tags

None

Referenced Files

	Unknown Object (File)
	Thu, Feb 13, 11:07 AM

	Unknown Object (File)
	Fri, Feb 7, 2:37 AM

	Unknown Object (File)
	Dec 14 2024, 8:36 PM

	Unknown Object (File)
	Dec 4 2024, 11:35 PM

	Unknown Object (File)
	Nov 25 2024, 7:44 PM

	Unknown Object (File)
	Nov 25 2024, 10:44 AM

	Unknown Object (File)
	Nov 21 2024, 8:21 AM

	Unknown Object (File)
	Nov 20 2024, 9:04 AM

View All 61 Files

Subscribers

imp

olce

Details

Reviewers

alc

Commits

rG749c249dc3b6: subr_pctrie: use ilog2(x) instead of fls(x)-1
rG574ef6506950: subr_pctrie: use ilog2(x) instead of fls(x)-1

Summary

In a GENERIC-NODEBUG kernel, each instance of using ilog2 in place of fls()-1 saves about 4 amd64 instructions, including a conditional, and 16 or so bytes.

Diff Detail

Lint

Lint Skipped

Unit

Tests Skipped

Event Timeline

dougm requested review of this revision.May 24 2024, 5:01 AM

dougm created this revision.

alc accepted this revision.May 24 2024, 5:59 AM

This revision is now accepted and ready to land.May 24 2024, 5:59 AM

Closed by commit rG574ef6506950: subr_pctrie: use ilog2(x) instead of fls(x)-1 (authored by dougm). · Explain WhyJun 3 2024, 5:50 PM

This revision was automatically updated to reflect the committed changes.

dougm added a commit: rG574ef6506950: subr_pctrie: use ilog2(x) instead of fls(x)-1.

Herald added subscribers: olce, imp. · View Herald TranscriptJun 3 2024, 5:50 PM

dougm added a reverting change: rGe3537f9235ba: Revert "subr_pctrie: use ilog2(x) instead of fls(x)-1".Jun 3 2024, 6:08 PM

dougm added a commit: rG749c249dc3b6: subr_pctrie: use ilog2(x) instead of fls(x)-1.Jun 3 2024, 6:32 PM

Revision Contents
Changeset List

Path

Size

sys/

kern/

subr_pctrie.c

6 lines

Diff 139023

View Options

subr_pctrie: use ilog2(x) instead of fls(x)-1ClosedPublicActions