From: Bill Davidsen <davidsen@tmr.com>
To: Lapo TIN <lapolapolapo@tin.it>
Cc: linux-smp@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: smp and irq conflict
Date: Fri, 02 Feb 2007 09:52:20 -0500 [thread overview]
Message-ID: <45C35024.8090907@tmr.com> (raw)
In-Reply-To: <45BE4003005C2845@vsmtp2.tin.it> (added by postmaster@virgilio.it)
Lapo TIN wrote:
> Dear all,
> I have a problem with IRQs.
>
> My pc has a CPU PentiumD945 (dual core) and a 2.6.19smp kernel.
> I have two video acquisition board (four bt8t8 each) in the only two pci
> slots of my motherboard. Thus I have a total of 8 bttv modules that are
> working together, and the /proc/interrupts is as follows:
> # cat /proc/interrupts
> CPU0 CPU1
> 0: 13575 0 IO-APIC-edge timer
> 1: 2 0 IO-APIC-edge i8042
> 4: 11 0 IO-APIC-edge serial
> 8: 1 0 IO-APIC-edge rtc
> 9: 0 0 IO-APIC-fasteoi acpi
> 12: 4 0 IO-APIC-edge i8042
> 14: 22286 0 IO-APIC-edge ide0
> 17: 7073 2097 IO-APIC-fasteoi uhci_hcd:usb5, eth0
> 18: 2525 0 IO-APIC-fasteoi bttv0, bttv7
> 19: 2829 0 IO-APIC-fasteoi bttv1, bttv4
> 20: 2526 0 IO-APIC-fasteoi bttv2, bttv5
> 21: 2226 0 IO-APIC-fasteoi bttv3, bttv6
> 22: 2 0 IO-APIC-fasteoi ehci_hcd:usb1, uhci_hcd:usb4
> 23: 86 0 IO-APIC-fasteoi uhci_hcd:usb2
> 24: 0 0 IO-APIC-fasteoi uhci_hcd:usb3
> NMI: 0 0
> LOC: 13484 13502
> ERR: 0
> MIS: 0
> You can see that IRQ18 is shared between bttv0 and bttv7, IRQ19 between
> bttv1 and bttv4 and so on.
>
> Sometimes it crashes. It seems a matter of conflict in IRQ.
> With only one video board everything is ok, but with two, they shared irq
> and something goes wrong...
> How can I tell to the kernel to not to share the IRQ for these boards ?
> I think (I don't know if I'm right) that this could be the problem.
>
> I even tried with another motherboard, and doing cat /proc/interrupts the
> situation was the same, except for 'eth0' that was together with bttv0 and
> bttv7... so it was even worst ! it crashes after few minutes.
>
> I tried to read IO-APIC.txt in Documentation/i386/ folder, but I didn't
> understand how to avoid the coupling of IRQ.
You may be able to move one board to another slot, but looking at the
bandwidth I suspect you may need a server motherboard with multiple
busses, preferably running at 66MHz 64bit. I don't think this is a
interrupt problem, but you can just try capture on two channels which
share an interrupt, like bttv0 and bttv7 to verify that.
I think you are just running out of bus.
--
bill davidsen <davidsen@tmr.com>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
next prev parent reply other threads:[~2007-02-02 14:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-01 17:46 smp and irq conflict Lapo TIN
2007-02-02 4:32 ` Andrew Morton
2007-02-02 4:32 ` Andrew Morton
2007-02-02 5:22 ` Len Brown
2007-02-02 14:52 ` Bill Davidsen [this message]
2007-02-05 10:33 ` Benny Amorsen
2007-02-14 16:45 ` Bill Davidsen
[not found] <fa.bd33YMixT9/jJwHfbD/DebGgVXs@ifi.uio.no>
2007-02-01 23:29 ` Robert Hancock
2007-02-02 0:04 ` Lapo TIN
2007-02-02 0:59 ` Robert Hancock
2007-02-02 11:08 ` Erik Mouw
2007-02-14 17:59 ` Manu Abraham
2007-02-02 0:04 ` Lapo TIN
2007-02-02 0:04 ` Lapo TIN
-- strict thread matches above, loose matches on Subject: below --
2007-02-01 17:46 Lapo TIN
2007-02-01 17:46 Lapo TIN
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