Reclaim unused ithread priorities for user time-sharing threads.
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Authored by jhb on Jun 28 2022, 10:32 PM.

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kib
markj

Commits

rGb62848b0c3ff: Reclaim unused ithread priorities for user time-sharing threads.

Summary

Leave one band of ithread priorities available below PI_SOFT for
demoted ithreads but reclaim additional ithread priorities for use by
user time-sharing threads. This is an ABI change in that PZERO moves
up so old ps and top binaries will not format priorities correctly on
newer kernels, but that is a cosmetic rather than functional change.

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rG FreeBSD src repository

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Event Timeline

jhb created this revision.Jun 28 2022, 10:32 PM

Herald added a subscriber: imp. · View Herald TranscriptJun 28 2022, 10:32 PM

jhb requested review of this revision.Jun 28 2022, 10:32 PM

Harbormaster completed remote builds in B46170: Diff 107509.Jun 28 2022, 10:32 PM

jhb added a parent revision: D35646: Collapse interrupt thread priorities..Jun 28 2022, 10:32 PM

I do not object, but IMO there is no urgent need to expand the timeshare user prio range. Might be, leave it to either ithr as is, basically reserving them if some more urgent need would appear?

This revision is now accepted and ready to land.Jul 2 2022, 9:40 AM

I agree there is not an urgent need, I was only doing this in response to the XXX comment above that I think @jeff added when adding ULE as he would have liked to have more priorities for userspace. I had mostly just tacked this onto the end of the earlier changes based on the XXX, not as a main feature. The main thing I care about in this series is the time-sharing to better handle livelock conditions.

markj accepted this revision.Jul 12 2022, 1:58 PM

markj added inline comments.