Re: SCHED_ULE on desktop system

On Sun, Sep 16, 2007 at 10:19:32AM +0400, Roman Bogorodskiy wrote:
> Hello,
> 
> 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 find SCHED_ULE to provide much better interactivity than SCHED_BSD on
my desktop.  Normally, I can have a couple of compiles and a bunch of
other stuff going on in the background and I can't even feel it, and
I'm on a UP p4.  I can, however, reproduce what you're talking about.
It's always something graphically intensive that gets it going, and it
only happens when there's a couple of compiles running in the background.
I tried to trigger it for hours doing a ton of stuff non-graphical,
including running a couple of jobs that made it go a gig into swap.
It handled everything nicely.  However, every time I do something like
start an opengl app and drag it around or start xlock, with compiles
in the background, things get very stuttery.  After closing the offending
app, it continues to be like that for a while, and eventually corrects
itself and goes back to normal.

I suspected xorg was maybe blocking on some writes to something but
looking at the kdump of xorg didn't reveal anything to me.

> However, when I switch to SCHED_4BSD, system's reaction time gets lower
> and I even can watch a movie with mplayer when compiling something.

I haven't tried SCHED_4BSD yet.  I'll have more time tomorrow.

Marcus