RE: [Xen-devel][RFC]degradation on IPF due to hypercall set irq

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Keir Fraser write on 2006年11月22日 17:26:
> On 22/11/06 09:24, "Xu, Anthony" <anthony.xu@xxxxxxxxx> wrote:
> 
>>>>> To clarify, by event/main loop I mean: Flush just before qemu
>>>>> blocks (otherwise multicall can be held for unbounded time,
>>>>> unless we set a batching timeout which hopefully we can avoid
>>>>> needing to do). 
>> 
>> Why otherwise multicall can be held for unbounded time?
> 
> Qemu only wakes up for device-model accesses. We don't know when the
> next of those will be. So we should flush multicalls before the
> potentially blocking select().

There are two threads, one is qemu thread, the other is IDE DMA thread,
In IDE DMA thread, when it finishing DMA opereration, it will set irq, but it
doesn't  try to wakeup qemu thread. So if qemu thread is sleeping at the same 
time,
this interrupt may be delivered until qemu thread wakes up, the time may be
10 msec.
So we need a mechanism for IDE DMA thread to wake up Qemu thread.

What's your opinion?

Thanks,
Anthony




> 
>  -- Keir

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