Re: [Xen-devel] [PATCH] x86 hvm: freeze PIT/LAPIC timer emulation while its IRQ is masked

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Although I can see the sense here, the patch makes me a bit uneasy. Also I
think neater code would result from simply making vpt.c's handling of
periodic timers less stupid. By this I mean that calling set_timer() from
the timer handler is not really necessary -- you already know an interrupt
is now pending and the vcpu is kicked. May as well not set_timer() until the
pending interrupt(s) are delivered. That would then effectively get your
optimisation "for free", wouldn't it?

 -- Keir

On 10/09/2009 06:47, "Kouya Shimura" <kouya@xxxxxxxxxxxxxx> wrote:

> Hi,
> 
> I've found that modern windows OS never use the PIT timer,
> and neither cpu#0's LAPIC timer after boot.
> Despite that, xen emulates them busily. It's inefficient.
> 
> Note: this patch ignores the IRQ mask of legacy i8259 since
> rombios frequently modifies it.
> 
> Thanks,
> Kouya
> 
> Signed-off-by: Kouya Shimura <kouya@xxxxxxxxxxxxxx>
> 



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel