X unresponsive with SCHED_ULE (was: Re: X becomes unresponsive with nvidia and hardlocks with gdb)

On Tue, 2009-01-13 at 13:34 +0100, Christoph Mallon wrote:
> O. Hartmann schrieb:
> > Garrett Cooper wrote:
> >> - I've rebuilt my xorg-server a few times and it's still claiming that
> >> it was built with 7.1-RC2 -_-...
> >> - I can get the Xorg server to go full tilt by just compiling
> >> something, like buildworld, via an xterm.
> >>   
> > I also experienced this, but not only with the mentioned 'nv' driver,
> > also with 'vesa'. Compiling a kernel or making buildworld, even with no
> > -jX option, turns the box sometimes in a state of unresponseness. Mouse
> > jumping, no keyboard response, sometimes for more than a minute. This
> > happens on a FBSD 8.0-CUR/AMD64 UP box and it also happens on a FreeBSD
> > 7.1-STABLE box (also amd64, 4 cores). But on SMP boxes I reralized that
> > the problem does not impact that harsh as seen on UP boxes.
> > We also had several P4 32bit machines with HTT enabled around, one of
> > them was built with FreeBSD 7.1-STABLE AND Xorg and I never realized the
> > bumpy X11, even when disabling HTT and running UP and Xorgs vesa driver.
> > 
> > Well, it also seems to make no difference whether I use USB2 stack (in
> > FreeBSD 8) or the old one.
> 
> I regularly can observe that batch jobs like large compile jobs get a 
> lower priority number (i.e. they get preferred by the scheduler) than X 
> on my UP machine with SCHED_ULE (7.0-STABLE from early July). Just a bit 
> X activity (switching desktops, scrolling in a browser etc.) is enough 
> to make its priority number higher than that of make+gcc.

Yes, ULE does still have a few issues, especially with jobs that should
have a low priority getting the CPU when higher priority jobs should
have it.  This is especially noticeable with processes that want to use
100% cpu but are supposed to run at idprio (a good example is
ports/misc/dnetc) - and is why my desktops are still using 4BSD.

If you can retest with SCHED_4BSD, it would be worth doing so.

Gavin