sched_4bsd: add static assertion for nice weight
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Authored by mchoo on Fri, Sep 4, 5:36 PM.

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jhb
olce

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scheduler

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rGe90be6fdf085: sched_4bsd: add static assertion for nice weight

Summary

When NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) exceeds the timeshare range,
two CPU-bound threads with different nice values can have the same
priority as their nice values are clamped to the timeshare range limit.
Add static assertion on NICE_WEIGHT to ensure that there is always
enough room for nice values in the both end of the timeshare priority
range.

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

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rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

mchoo created this revision.Fri, Sep 4, 5:36 PM

Herald added subscribers: olce, imp. · View Herald TranscriptFri, Sep 4, 5:36 PM

mchoo requested review of this revision.Fri, Sep 4, 5:36 PM

Harbormaster completed remote builds in B76504: Diff 185832.Fri, Sep 4, 5:36 PM

mchoo added a parent revision: D59395: sched_4bsd: remove dumping from maybe_preempt().Fri, Sep 4, 5:36 PM

mchoo added a child revision: D59397: sched_4bsd: update function name in comment.

Please rephrase though the assertion description (see inline comment).

sys/kern/sched_4bsd.c
77	I'd suggest rephrasing this to be more high-level (in general, the text should not repeat what can be readily inferred from the test itself to have enough added value).

This revision is now accepted and ready to land.Sun, Sep 6, 4:14 PM

Closed by commit rGe90be6fdf085: sched_4bsd: add static assertion for nice weight (authored by mchoo). · Explain WhyFri, Sep 18, 2:15 PM

This revision was automatically updated to reflect the committed changes.

mchoo added a commit: rGe90be6fdf085: sched_4bsd: add static assertion for nice weight.