Odd performance problem (hitching)

Bill Paul wpaul at FreeBSD.ORG
Thu Sep 8 11:58:09 PDT 2005


> > > 
> > >>That could be an important clue.  Maybe one of the X apps that you are
> > >>running, like your mail reader, browser, or system status monitor.  Try
> > >>running X with one of the lightweight window managers and just an xterm
> > >>or two.
> > >>
> > >>The 10 second interval doesn't make it sound like the problem is any of
> > >>the built in kernel tasks.  It's more consistent with something that
> > >>runs every 10 seconds in userland that monopolizes some kernel resource
> > >>whenever it runs.
> > > 
> > > 
> > > Possibly, but I would expect to see some evidence in top of this.
> > > 
> > > Also, during the 'lag' X drops or doubles up keypresses - it would suprise me 
> > > to find that a userland app could make X do that very easily.
> > > 
> > > I will try your suggestion though.
> > 
> > I had a similar problem with XFCE4's battery/temp monitor applet.  I 
> > think my freeze was about every 6-10seconds.
> 
> I've also had a problem with gnome's battery monitor producing long
> "hitches" every several seconds.

*sigh*

The problem is the ACPI thermal monitor thread. Once every 10 seconds,
it queries the thermal state of the system, and reading this state
seems to chew up a lot of cycles with interrupts blocked.

You can shut it up by editing loader.conf and adding:

debug.acpi.disable="thermal"

But the correct thing to do is fix the code that access ACPI
resources/registers/whatever so that it doesn't block for so
long. I'm really very annoyed that nobody has bothered to
address this yet.

-Bill

--
=============================================================================
-Bill Paul            (510) 749-2329 | Senior Engineer, Master of Unix-Fu
                 wpaul at windriver.com | Wind River Systems
=============================================================================
              <adamw> you're just BEGGING to face the moose
=============================================================================


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