* [Qemu-devel] Re: UIO interrupts being lost
[not found] <AANLkTinBUBSDM-SQXt64CGrF2TBcGPoJQKPojk5N9FCY@mail.gmail.com>
@ 2010-06-25 10:32 ` Michael S. Tsirkin
0 siblings, 0 replies; only message in thread
From: Michael S. Tsirkin @ 2010-06-25 10:32 UTC (permalink / raw)
To: Cam Macdonell, kvm, qemu-devel
On Thu, Jun 24, 2010 at 05:43:15PM -0600, Cam Macdonell wrote:
> Hi Michael,
>
> I'm trying to write a uio driver for my shared memory device for KVM
> and I'm running into a situation where several interrupts in quick
> succession are not all triggering the callback function in my kernel
> UIO driver, say 2 out of 5. My driver does not set the Interrupt
> Disable bit and if it helps, I'm using MSI-X interrupts. Even without
> the interrupt disable bit set, is there still a window where
> successive interrupts can be lost if they arrive too quickly?
>
> Thanks,
> Cam
Yes, I think so: if an interrupt is delivered when
ISR is running, it gets queued, but a second one
gets lost.
A queueing mechanism is necessary to avoid losing
information, e.g. virtio implements exactly that.
Why don't you reuse virtio for signalling?
If I understand what Anthony said correctly,
he objected to the specific implementation,
not to the idea of reusing virtio spec and code.
--
MST
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