Re: Interrupt storm with MSI in combination with em1

On Thursday 05 May 2011 00:15:43 you wrote:
> This all looks completely kosher,  what IRQ is the storm on??

IRQ 16. Further down this email there is a list of devices that share the IRQ 
according to 'dmesg'.


> On Wed, May 4, 2011 at 3:04 PM, Daan Vreeken <Daan_at_vehosting.nl> wrote:
> > Hi,
> >
> > On Wednesday 04 May 2011 20:47:32 Jack Vogel wrote:
> > > Will you please set it back to a default and then boot and capture the
> > > message for me?
> >
> > No problem. Here's the output with MSI/MSIX enabled :
> >
> > http://vehosting.nl/pub_diffs/dmesg_plantje2_with_msix_2011_05_04.txt
> >
> > I've also added the output of "vmstat -i" a couple of minutes after a
> > reboot
> > with MSI enabled :
> >        http://vehosting.nl/pub_diffs/vmstat_i_2011_05_04.txt
> >
> > Note that in the above "vmstat -i" dump the interrupt storm hasn't
> > started yet. For some reason the storm doesn't always start directly at
> > boot. I haven't been able (yet) to pinpoint what's triggering it to
> > start.
> >
> > > On Wed, May 4, 2011 at 11:19 AM, Daan Vreeken <Daan_at_vehosting.nl> wrote:
> > > > 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


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