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Differential D59401

sched: fix kern.sched.{4bsd,ule}.slice
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Authored by mchoo on Sep 4 2026, 5:37 PM.
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imp
olce

Details

Reviewers
jhb
olce
Group Reviewers
scheduler
Commits
rGc087ee05b525: sched: fix kern.sched.{4bsd,ule}.slice
rGa97fea97e351: sched: fix kern.sched.{4bsd,ule}.slice
rG179f5b2bfedc: sched: fix kern.sched.{4bsd,ule}.slice
Summary

Fix three problems with kern.sched.{4bsd,ule}.slice:

  • Guarantee minimum slice is 1.
  • Recalculate hogticks on sysctl write.
  • For ULE, recalculate sched_slice_min on sysctl write.

MFC after: 2 weeks
MFC to: stable/14, stable/15
Sponsored by: FreeBSD Foundation

Diff Detail

Repository
rG FreeBSD src repository
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Lint Skipped
Unit
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Build Status
Buildable 76509
Build 73392: arc lint + arc unit

Event Timeline

mchoo created this revision.Sep 4 2026, 5:37 PM
Herald added subscribers: olce, imp. · View Herald TranscriptSep 4 2026, 5:37 PM
mchoo requested review of this revision.Sep 4 2026, 5:37 PM
Harbormaster completed remote builds in B76509: Diff 185837.Sep 4 2026, 5:37 PM
mchoo added a parent revision: D59400: sched_ule: fix typo goup to group.Sep 4 2026, 5:37 PM
mchoo added a child revision: D59402: sched_4bsd: fix comment in maybe_preempt().
olce requested changes to this revision.Sun, Sep 6, 4:38 PM
olce added inline comments.
sys/kern/sched_4bsd.c
214

It's an internal function, no need to have 4bsd_ in the name.

Additionally, I'm planning to rename back all implementations of the current interface (to the rest of the kernel) to their prior names, that is, with ule_ or 4bsd_ removed, relatively soon (but there is EuroBSDCon next week).

224

Not necessary given the previous test. Replace by an assertion?

225–226

Could you please factor out the hogticks computation and setting in a separate function, and use it throughout the file (preferably as a separate commit)?

sys/kern/sched_ule.c
3490–3502

Same comments as for 4BSD.

This revision now requires changes to proceed.Sun, Sep 6, 4:38 PM
mchoo updated this revision to Diff 186038.Sun, Sep 6, 9:02 PM

Remove unnecessary imax()

Harbormaster completed remote builds in B76611: Diff 186038.Sun, Sep 6, 9:02 PM
mchoo added inline comments.Sun, Sep 6, 9:02 PM
sys/kern/sched_4bsd.c
214

Since sysctl_kern_4bsd_quantum already has the namespace, I'll keep it for now. It can be renamed when the cleanup is done across 4BSD and ULE.

224

I think assertion is unnecessary here.

sys/kern/sched_ule.c
3499

D59408 adds imax() check for quantum sysctl.

olce added inline comments.Sun, Sep 6, 9:37 PM
sys/kern/sched_4bsd.c
214

Let's go right now in the intended direction. Additionally, having 4bsd_ here and no ule_ below is inconsistent. So please remove it.

mchoo updated this revision to Diff 186083.Sun, Sep 6, 10:42 PM

Remove namespacing

Harbormaster completed remote builds in B76617: Diff 186083.Sun, Sep 6, 10:42 PM
mchoo marked 4 inline comments as done.Sun, Sep 6, 10:42 PM
mchoo marked an inline comment as done.Sun, Sep 6, 10:52 PM
mchoo added inline comments.
sys/kern/sched_4bsd.c
225–226

Done in D59471

olce accepted this revision.Tue, Sep 8, 7:49 AM
This revision is now accepted and ready to land.Tue, Sep 8, 7:49 AM
Closed by commit rG179f5b2bfedc: sched: fix kern.sched.{4bsd,ule}.slice (authored by mchoo). · Explain WhyFri, Sep 18, 2:15 PM
This revision was automatically updated to reflect the committed changes.
mchoo marked an inline comment as done.
mchoo added a commit: rG179f5b2bfedc: sched: fix kern.sched.{4bsd,ule}.slice.
mchoo added a commit: rGa97fea97e351: sched: fix kern.sched.{4bsd,ule}.slice.Fri, Oct 2, 3:35 PM
mchoo added a commit: rGc087ee05b525: sched: fix kern.sched.{4bsd,ule}.slice.Fri, Oct 2, 3:50 PM

Revision Contents
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PathSize
sys/
kern/
21 lines
22 lines

Diff 185837

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sys/kern/sched_4bsd.c

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sys/kern/sched_ule.c

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