Re: [REPORT] cfs-v4 vs sd-0.44

Willy Tarreau
2007-04-24T17:46:07Z

On Tue, Apr 24, 2007 at 10:38:32AM -0400, Gene Heskett wrote:
> On Tuesday 24 April 2007, Ingo Molnar wrote:
> >* David Lang <david.lang@digitalinsight.com> wrote:
> >> > (Btw., to protect against such mishaps in the future i have changed
> >> > the SysRq-N [SysRq-Nice] implementation in my tree to not only
> >> > change real-time tasks to SCHED_OTHER, but to also renice negative
> >> > nice levels back to 0 - this will show up in -v6. That way you'd
> >> > only have had to hit SysRq-N to get the system out of the wedge.)
> >>
> >> if you are trying to unwedge a system it may be a good idea to renice
> >> all tasks to 0, it could be that a task at +19 is holding a lock that
> >> something else is waiting for.
> >
> >Yeah, that's possible too, but +19 tasks are getting a small but
> >guaranteed share of the CPU so eventually it ought to release it. It's
> >still a possibility, but i think i'll wait for a specific incident to
> >happen first, and then react to that incident :-)
> >
> > Ingo
>
> In the instance I created, even the SysRq+b was ignored, and ISTR thats
> supposed to initiate a reboot is it not? So it was well and truly wedged.

On many machines I use this on, I have to release Alt while still holding B.
Don't know why, but it works like this.

Willy