kern/141721: (id|rt)prio priority resets when new thread is created

Volodymyr Kostyrko c.kworr at
Thu Dec 17 19:20:04 UTC 2009

>Number:         141721
>Category:       kern
>Synopsis:       (id|rt)prio priority resets when new thread is created
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Dec 17 19:20:03 UTC 2009
>Originator:     Volodymyr Kostyrko
>Release:        RELENG_8
FreeBSD limbo.lan 8.0-STABLE FreeBSD 8.0-STABLE #0: Thu Dec 17 12:42:39 EET 2009     arcade at limbo.lan:/usr/obj/usr/src/sys/MINIMAL_8  i386
I'm just curious about this one.

I've got a big bunch mail and news on my home computer. On ZFS with compression my mail profile weights 250Mb. I prefer to use seamonkey. But sometimes after update seamonkey tries to compress mail folders which can be huge. With 20 threads seamonkey effectively blocks my computer from doing anything.

The simple solution I tried was idling seamonkey for 1 level with idprio 1 -pid. But I was very surprised that one minute later top shows that seamonkey has normal priority. Checking top continuously I realiased that each time a new thread starts the priority resets to normal. Running idprio 1 -pid again sets priority and I can see that in top. But few moments later priority returns to normal again.
Trying to run a program that creates threads with idprio and checking the status of it would suffice.
I'm not familiar with threading kernel code so I can't even imagine where the problem is.


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