Re: 13-STABLE high idprio load gives poor responsiveness and excessive CPU time per task

On 2024-02-27, Edward Sanford Sutton, III <mirror176@hotmail.com> wrote:
>    More recently looked and see top showing threads+system processes 
> shows I have one core getting 100% cpu for kernel{arc_prune} which has 
> 21.2 hours over a 2 hour 23 minute uptime.

Ack.

> I started looking to see if 
> https://www.freebsd.org/security/advisories/FreeBSD-EN-23:18.openzfs.asc 
> was available as a fix for 13 but it is not (and doesn't quite sound 
> like it was supposed to apply to this issue). Would a kernel thread time 
> at 100% cpu for only 1 core explain the system becoming unusually 
> unresponsive?

That depends. This arc_prune issue does usually go alongside with some
other kernel thread (vm-whatever) also blocking, so you have two cores
busy. How many remain?

There is an updated patch in the PR 275594 (5 pieces), that works for
13.3; I have it installed, and only with that I am able to build gcc12
 - otherwise the system would just OOM-crash (vm.pageout_oom_seq=5120
does not help with this).

I didn't see any lagging behaviour, but then, I have 20 vCore.

cheerio,
PMc