Date: Wed, 19 Mar 2008 16:32:13 -0400 From: Mike Tancsa <mike@sentex.net> To: Jeremy Chadwick <koitsu@freebsd.org>, freebsd-stable@freebsd.org, root@ha-web1.hockeyarena.net Subject: Re: Weird system cpu usage Message-ID: <200803192034.m2JKYFmL087217@lava.sentex.ca> In-Reply-To: <20080319180629.GA29308@eos.sc1.parodius.com> References: <669936444.20080319100148@rulez.sk> <200803191753.m2JHraI5092556@lurza.secnetix.de> <20080319180629.GA29308@eos.sc1.parodius.com>
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At 02:06 PM 3/19/2008, Jeremy Chadwick wrote:
>On Wed, Mar 19, 2008 at 06:53:36PM +0100, Oliver Fromme wrote:
> > Charlie Root <root@ha-web1.hockeyarena.net> wrote:
> > > root@[ha-web1 ~]# vmstat -i
> > > interrupt total rate
> > > irq1: atkbd0 12 0
> > > irq16: ohci0 1 0
> > > irq17: ohci1 ohci3 1 0
> > > irq18: ohci2 ohci4 1 0
> > > irq20: em0 86255835 1361
> > > irq22: em1 atapci0 18611379049 293795
> >
> > Now that looks unusual indeed. Do you get that rate
> > on irq22 right after boot, before the services have
> > started? It looks like either hardware or driver
> > problems. Do you have polling enabled on em1?
>
>Also, I believe there was a report from another user who saw similar
>issues with em(4), and found that disabling MSI fixed the storm in
>question. I believe you can disable MSI/MSIX by placing the following
>in /boot/loader.conf, then reboot:
>
>hw.pci.enable_msi="0"
>hw.pci.enable_msix="0"
When MSI is enabled, the irq will be a strangely high number. e.g.
% vmstat -i
interrupt total rate
irq4: sio0 76 0
irq17: em3 360 0
irq19: atapci1 2901 0
cpu0: timer 33719800 1999
irq257: em1 56571 3
irq258: em2 4 0
cpu1: timer 33717664 1999
Total 67497376 4003
If anything, I found enabling MSI helped matters where I saw strange
IRQ issues. However, not sure if the original poster's hardware
supports it. One thing it does remind me of is some strange IRQ
issues I had on an AMD board where a USB setting for "legacy handoff"
(something like that) would really slow down the machine with an in
inordinate amount of IRQs firing. I forget if I had to enable it or
disable it to fix the problem. If anything, I would try disabling
USB all together if its not being used even though its not figuring
in the above really high rate of IRQs.
---Mike
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