Strange pauses and cpu usage - FreeBSD 6.1

[Danial Thom]

--- Shawn <shawnh at f2s.com> wrote:

> On Sun, 28 May 2006 01:02:35 -0400
> Kris Kennaway <kris at obsecurity.org> wrote:
> 
> > On Sun, May 28, 2006 at 02:18:36AM +0200,
> Xavier Chantry wrote:
> > > On Sat, May 27, 2006 at 01:14:13AM +0100,
> Shawn wrote:
> > > > I'm having a strange problem with cpu
> usage with my Athlon XP.
> > > > Every so often there seems to be a pause
> where the system comes
> > > > under heavy load for no apparent reason.
> If xmms was playing then
> > > > I get a buzz sound and the mouse pointer
> stops just for a split
> > > > second, the same with mplayer and vlc.
> Using Opera or firefox
> > > > also seems to have a strange effect where
> the mouse pointer
> > > > freezes while pages load, and if there is
> an animated gif on the
> > > > page the cpu usage goes to 100%.
> > > > 
> > > > The jabber client Gajim also makes the
> cpu get stuck at 100%.
> > > > When I used gnome, nautilus did the same
> thing until i stopped
> > > > and started the process in the system
> monitor. I have searched
> > > > around and found this tip from the
> handbook but it had no effect.
> > > > 
> > > > hint.apic.0.disabled="1" in
> /boot/loader.conf
> > > > 
> > > > This happens with the generic kernel and
> the one i compiled for
> > > > myself. It also lasts for a random amount
> of time, sometimes it
> > > > is barely noticeable and sometimes it
> happens for over a second.
> > > > Running neverwinter nights makes the
> system pause for 10-20
> > > > seconds seemingly randomly.
> > > > 
> > > 
> > > My system behaves much better than that,
> I've no mouse freeze and no
> > > system pauses, but I did have occasonial
> sound skips using 4bsd on
> > > 6.1. Switching to the ULE scheduler seems
> to fix this problem, but
> > > other things may behave worse.
> > > One year ago, it was actually the opposite,
> sound in ULE was really
> > > jerky, and mouse pointer too while eg
> launching an app.
> > > Did you already try both schedulers ?
> > 
> > Check for interrupt sharing with vmstat -i. 
> Shared interrupts cause
> > performance loss especially if it's sharing
> with a giant-locked driver
> > like USB.
> > 
> > Kris
> 
> I tried switching to ULE and while the sound
> skipping seems to have
> stopped, the other problems remain.
> 
> vmstat -i gives me:
> 
> interrupt                          total      
> rate
> irq0: clk                          69873       
> 984
> irq7: ppc0                             2       
>   0
> irq8: rtc                           8944       
> 125
> irq10: atapci0++                    2409       
>  33
> irq11: nvidia0++                    5264       
>  74
> irq12: pcm0 rl0+                      41       
>   0
> irq15: ata1                           47       
>   0
> Total                              86580      
> 1219
> 
> So it seems that net and sound are sharing
> irq12, and just before i
> see the freeBSD bootloader i can see that irq12
> is used for the usb
> controller. Is this my problem? I have no irq
> settings in the
> BIOS and i tried a device hint for pcm to move
> it up to irq13 but had no
> luck.
> 
> Forgive me if I am missing something obvious
> somewhere along the line,
> I only started using freeBSD a few weeks ago
> and I am totally new to
> BSD in general.
> 
> Thanks for the help!
> 
> ~shawn

Setting HZ to 100 should eliminate ~900
unnecessary context switches per second. 

Danial

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