interrupt storm on ahci

[Neel Natu]

Hi Steve,

On Sat, Jun 7, 2014 at 2:28 PM, Peter Grehan <grehan at freebsd.org> wrote:
> Hi Steve,
>
>
>> I'm running a FreeBSD guest in bhyve on a FreeBSD host. Both are running
>> FreeBSD CURRENT, r266947. I've gotten this message about 12 times since
>> boot:
>>
>> interrupt storm detected on "irq268:"; throttling interrupt source
>>
>> vmstat -i shows:
>>
>> irq268: ahci1                  236514222        839
>>
>> ahci1 is the second disk connected to the system:
>>
>> ahci1: <Intel ICH8 AHCI SATA controller> mem 0xc0002400-0xc00027ff irq 18
>> at device 4.0 on pci0
>>
>> The VM itself runs poudriere and was building a bunch of packages. At the
>> moment, the VM seems to be in a rather odd state. The poudriere jails are
>> running, but not doing anything. Ideas?
>
>
>  Is this an 8.* host ? I don't believe AHCI has MSI support on that version,
> and AHCI legacy interrupts haven't had a huge amount of testing under load.
>
>  If it is 8.*, I'd recommend using virtio-blk for the block device until we
> can work out what's going wrong.
>

The KTR trace would be useful to figure out what's happening.

To do that you can compile the host kernel and vmm.ko with the
following options:
options KTR
options KTR_MASK=(KTR_GEN)
options KTR_ENTRIES=(4*1024*1024)

And when you see the interrupt storm message in the guest you can execute:
sudo ktrdump -cto /tmp/ktrdump.out

best
Neel

> later,
>
> Peter.
>
>
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