Page MenuHomeFreeBSD
Differential D17851

Add a custom implementation of cpu_lock_delay() for x86.
ClosedPublic
Actions

Authored by jhb on Nov 5 2018, 6:13 PM.
Tags
None
Referenced Files
F133130775: D17851.id50046.diff
Thu, Oct 23, 5:30 AM
F133130772: D17851.id.diff
Thu, Oct 23, 5:30 AM
F133130770: D17851.id50042.diff
Thu, Oct 23, 5:30 AM
F133089991: D17851.id50034.diff
Wed, Oct 22, 9:29 PM
Unknown Object (File)
Wed, Oct 22, 12:05 PM
Unknown Object (File)
Sat, Oct 18, 4:03 PM
Unknown Object (File)
Thu, Oct 16, 3:24 PM
Unknown Object (File)
Wed, Oct 1, 1:42 PM
View All Files
Subscribers
imp
rpokala

Details

Reviewers
kib
Commits
rS340170: Add a custom implementation of cpu_lock_delay() for x86.
Summary

Avoid using DELAY() since it can try to use spin locks on CPUs without a
P-state invariant TSC. For cpu_lock_delay(), always use the TSC if it
exists (even if it is not P-state invariant) to delay for a microsecond.
If the TSC does not exist, read from I/O port 0x84 to delay instead.

PR: 228768

Test Plan
  • passed make tinderbox (aside from unrelated breakage in arm.GENERIC-NODEBUG)
  • booted in i386 and amd64 VMs
  • original PR reporter booted combined patch on amd64 machine

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint Not Applicable
Unit
Tests Not Applicable

Event Timeline

jhb created this revision.Nov 5 2018, 6:13 PM
Harbormaster completed remote builds in B20642: Diff 50034.Nov 5 2018, 6:13 PM
jhb added a parent revision: D17850: Add a delay_tsc() static function for when DELAY() uses the TSC..Nov 5 2018, 6:14 PM
kib accepted this revision.Nov 5 2018, 9:21 PM
kib added inline comments.
sys/x86/x86/delay.c
125 ↗(On Diff #50034)

And there a comment why tsc_is_invariant check is omitted would be useful IMO.

This revision is now accepted and ready to land.Nov 5 2018, 9:21 PM
jhb updated this revision to Diff 50042.Nov 5 2018, 9:43 PM

Expand comment.

This revision now requires review to proceed.Nov 5 2018, 9:43 PM
Harbormaster completed remote builds in B20646: Diff 50042.Nov 5 2018, 9:43 PM
jhb marked an inline comment as done.Nov 5 2018, 9:44 PM
kib accepted this revision.Nov 5 2018, 9:59 PM
This revision is now accepted and ready to land.Nov 5 2018, 9:59 PM
Closed by commit rS340170: Add a custom implementation of cpu_lock_delay() for x86. (authored by jhb). · Explain WhyNov 5 2018, 10:54 PM
This revision was automatically updated to reflect the committed changes.
Herald added subscribers: rpokala, imp. · View Herald TranscriptNov 5 2018, 10:54 PM

Revision Contents
Changeset List

PathSize
head/
sys/
amd64/
include/
2 lines
i386/
include/
2 lines
x86/
x86/
19 lines

Diff 50046

View Options

head/sys/amd64/include/cpu.h

Loading...
View Options

head/sys/i386/include/cpu.h

Loading...
View Options

head/sys/x86/x86/delay.c

Loading...