RE: [Xen-devel] Interrupt to CPU routing in HVM domains - again

[bart brooks <bart_brooks@xxxxxxxxxxx>]

Hi James,
 
We make the change and it did not help the perf issue; as result
 
Bart

> Subject: RE: [Xen-devel] Interrupt to CPU routing in HVM domains - again
> Date: Sat, 6 Sep 2008 22:21:47 +1000
> From: james.harper@xxxxxxxxxxxxxxxx
> To: bart_brooks@xxxxxxxxxxx; keir.fraser@xxxxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx
>
> Bart,
>
> I'm pretty sure I've identified the problem. The fact that the output of
> the debugging patch I sent you shows that sometimes one xennet isr is
> logged and sometimes two are logged was a bit of a clue. I assume you
> have two network adapters?
>
> Please make the following change to xennet.c:
>
> "
> diff -r ea14db3ca6f2 xennet/xennet.c
> --- a/xennet/xennet.c Thu Sep 04 22:31:38 2008 +1000
> +++ b/xennet/xennet.c Sat Sep 06 22:14:36 2008 +1000
> @@ -137,7 +137,7 @@ XenNet_InterruptIsr(
> else
> {
> *QueueMiniportHandleInterrupt = (BOOLEAN)!!xi->connected;
> - *InterruptRecognized = TRUE;
> + *InterruptRecognized = FALSE;
> }
>
> //FUNCTION_EXIT();
> "
>
> Xennet's isr was reporting that the interrupt was handled, which it was,
> but xennet needs to report that it was not handled so that the next isr
> in the chain is triggered. Your change to the isr in evtchn.c would have
> caused spurious interrupts which had the side effect of ensuring that
> the second xennet isr was triggered eventually.
>
> I hope that makes sense. I'm too tired to re-read it to make sure :)
>
> I'm not completely sure if it will work... I don't know how ndis will
> react when we tell it that it needs to schedule a dpc even though we are
> also telling it that the interrupt was not for us.
>
> Let me know the outcome and I'll release an update if it works.
>
> Thanks
>
> James
>

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