Re: SCHED_ULE on desktop system

> Date: Sun, 16 Sep 2007 14:47:54 -0700
> From: "David E. Thiel" <lx_at_FreeBSD.org>
> Sender: owner-freebsd-current_at_freebsd.org
> 
> On Sun, Sep 16, 2007 at 12:58:33AM -0700, vehemens wrote:
> > On Saturday 15 September 2007 11:19:32 pm Roman Bogorodskiy wrote:
> > >I'm curious if SCHED_ULE is designed to be used on a desktop system. I'm
> > >running -CURRENT at home and tried to use SCHED_ULE for some time. It
> > >works alright while the load is not very high. But once I start
> > >compiling something (running 'make buildworld' or 'portupgrade -a' for
> > >example), the machine comes almost unusable - X11's windows takes a lot
> > >of time to redraw, changing virtual desktop in window manager may take
> > >a several seconds. And it's nearly impossible to watch some movie with
> > >mplayer.
> > 
> > I also see something similar running -CURRENT with SCHED_4BSD,
> > but it shows up with X/gnome.  Remote logins are still responsive
> > and running X/twm works fine.
> 
> In my experience, both 4BSD and ULE are unresponsive on the desktop
> in -CURRENT, with ULE being somewhat worse. Compiling an application
> causes the mouse to be jerky, windows to draw slowly, audio to start
> skipping, and occasionally the whole desktop freezes for a minute at
> a time (with ULE only). This is with INVARIANTS and all the debugging
> kernel options disabled and malloc debugging turned off. 
> 
> I'll give running without PREEMPTION with 4BSD and the ULE patch a shot,
> but in its stock form, -CURRENT is definitely worse than -STABLE on the
> desktop for me in a UP configuration. Up till now, I've been working
> around it manually by juggling with rtprio.
> 
> If it's of any use, dmesg is at:
> 
> http://redundancy.redundancy.org/dmesg.txt

I have been seeing this for quite some time and, while the scheduler may
make a bit of difference, I suspect pager issues. As long as I have
available memory, interactivity is fine. If I run a big build and I see
swap file use, things slow to a crawl. I see very slow re-draws of the
screen and general lack of responsiveness.

I run gkrellm and can tell at a glance when swap usage starts to
increase. The linkage is clear and not terribly surprising. It may be
that you need to add a bit more RAM.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
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