Re: [RFC]degradation on IPF due to hypercall set irq

[Keir Fraser <keir@xensource.com>]

On 22/11/06 09:38, "Xu, Anthony" <anthony.xu@intel.com> wrote:

> 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?

Did the IDE code really need to made multithreaded? I suppose it's a better
model for the stub domain plans...  Anyway, it's a pain here because it will
require the shadow wire bitmap to be updated with atomic accesses and the
multicall state to be per-thread or to be protected with a mutex. Each
thread should flush multicall state before it blocks.

 -- Keir