Re: Interrupt storm with MSI in combination with em1

Hi Jack,

Wednesday 04 May 2011 19:46:05 Jack Vogel wrote:
> Who makes your motherboard? The problem you are having is that MSIX AND
> MSI are both failing as em0 comes up, so it falls back to Legacy interrupt
> mode,
> and must be having some issue with sharing the line, causing the storm.

The motherboard is an Asus "P7H55-M".
Sorry, I should have mentioned that the dmesg output is from booting with :

> >        hw.pci.enable_msix="0"
> >        hw.pci.enable_msi="0"

.. in "loader.conf".

With those lines in "loader.conf", MSI and MSIX is disabled, both cards work 
like they should and there is no interrupt storm.

With MSI/MSIX enabled, both cards work like they should and I see the counters 
of the MSI interrupts increase (in small amounts, like they should), but at 
boot-time an interrupt storm starts on 'legacy' IRQ 16.

Because the only difference between disabling/enabling MSI/MSIX seems to be in 
the way em0/em1 are used, and because 'em1' shares IRQ 16 according to the 
dmesg, I'm suspecting 'em1' is causing the storm.
(But please correct me if I'm wrong :)

What can I do to help track this problem down?

> >
> > According to "dmesg" the following devices share IRQ 16 :
> >
> >        pcib1: <ACPI PCI-PCI bridge> irq 16 at device 1.0 on pci0
> >        em0: <Intel(R) PRO/1000 Network Connection 7.2.3> port
> > 0xcc00-0xcc1f mem
> > 0xf7de0000-0xf7dfffff,0xf7d00000-0xf7d7ffff,0xf7ddc000-0xf7ddffff
> >           irq 16 at device 0.0 on pci1
> >        vgapci0: <VGA-compatible display> port 0xbc00-0xbc07
> >           mem 0xf7800000-0xf7bfffff,0xe0000000-0xefffffff irq 16 at
> > device 2.0 on
> >           pci0
> >        ehci0: <Intel PCH USB 2.0 controller USB-B> mem
> > 0xf7cfa000-0xf7cfa3ff
> >           irq 16 at device 26.0 on pci0
> >        em1: <Intel(R) PRO/1000 Network Connection 7.2.3> port
> > 0xec00-0xec1f mem
> > 0xf7fe0000-0xf7ffffff,0xf7f00000-0xf7f7ffff,0xf7fdc000-0xf7fdffff
> >           irq 16 at device 0.0 on pci4
> >        pcib4: <ACPI PCI-PCI bridge> irq 16 at device 28.5 on pci0
> >
> > During a storm "vmstat -i" shows a rate of about 220.000 interrupts/sec.
> > MSI
> > interrupt delivery to both 'em0' and 'em1' seems to work correctly during
> > a storm, as I see their counters increase normally in the "vmstat -i"
> > output.
> >
> > As only 'em0' and 'em1' seem to be using MSI interrupts, my guess is that
> > the
> > e1000 driver is causing this problem. Could it be that the driver forgets
> > to
> > clear/mask legacy interrupts when attaching the MSI interrupts perhaps?
> >
> > Any tips on how to debug and/or fix this?
> >
> >
> > The full output of "dmesg" can be found here :
> >        http://vehosting.nl/pub_diffs/dmesg_plantje2_2011_05_04.txt
> >
> > And the full output of "pciconf -lv" is here :
> >        http://vehosting.nl/pub_diffs/pciconf_plantje2_2011_05_04.txt
> >


Regards,
-- 
Daan Vreeken
VEHosting
http://VEHosting.nl
tel: +31-(0)40-7113050 / +31-(0)6-46210825
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