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Date:      Sun, 18 Jul 2010 12:19:21 +0200
From:      Bernd Walter <ticso@cicely7.cicely.de>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        Doug Barton <dougb@freebsd.org>, Rui Paulo <rpaulo@freebsd.org>, freebsd-current@freebsd.org
Subject:   Re: Why is intr taking up so much cpu?
Message-ID:  <20100718101920.GC17125@cicely7.cicely.de>
In-Reply-To: <20100717192128.GM2381@deviant.kiev.zoral.com.ua>
References:  <alpine.BSF.2.00.1007170013191.7378@qbhto.arg> <A81B337F-5932-44B1-BDB4-D9DD36332A16@lavabit.com> <alpine.BSF.2.00.1007171103060.1546@qbhto.arg> <F653FF83-D9CF-42A2-AE9A-B8F914090065@FreeBSD.org> <alpine.BSF.2.00.1007171208010.1538@qbhto.arg> <20100717192128.GM2381@deviant.kiev.zoral.com.ua>

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On Sat, Jul 17, 2010 at 10:21:28PM +0300, Kostik Belousov wrote:
> On Sat, Jul 17, 2010 at 12:10:26PM -0700, Doug Barton wrote:
> > On Sat, 17 Jul 2010, Rui Paulo wrote:
> > 
> > >This doesn't indicate any problem. I suggest you try to figure out what 
> > >interrupt is causing this by adding printfs or disabling drivers one by 
> > >one.
> > 
> > I've no idea where to even begin on something like that. Given that 
> > there are other -current users who are also having problems 
> > (particularly with the nvidia drivers) I'm wondering if some sort of 
> > systemic debugging isn't in order here?
> > 
> 
> Note that intr time most likely come from the interrupt threads chewing
> the CPU, not from the real interrupt handlers doing something, and definitely
> not due to the high interrupt rate, as your vmstat -i output already shown.

I've noticed a few webpages to trigger lot of X11 related network traffic
just by watching them even without any seeable content change, but CPU
load on browser and especialy X process went high, but of course
symptoms might be different with different drivers - I use mga myself.
I never analysed it properly beacuse I'm using a quite old Xorg version,
but I see the increase of traffic on the domain socket.
I also noticed that recent firefox and seamonkey are doing lots of NFS
traffic, so I was forced to switch ~/.mozilla to a local disk, where
iostat still stays idle.
But my OS is also not very recent, so I also never debugged this problem.

> Run top in the mode where all system threads are shown separately
> (e.g. top -HS seems to do it), then watch what thread eats the processor.



-- 
B.Walter <bernd@bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.



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