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[Xen-devel] Re: [PATCH] x86 hvm: fix missing ticks issue in c/s 20218

To: Kouya Shimura <kouya@xxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] x86 hvm: fix missing ticks issue in c/s 20218
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 25 Sep 2009 10:55:22 +0100
Cc: Christoph Egger <Christoph.Egger@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 25/09/2009 10:32, "Kouya Shimura" <kouya@xxxxxxxxxxxxxx> wrote:

> I've forgotten VCPU switch. Indeed, it's pretty fragile. :-)
> What about modifying pt_restore_timer() not to advance pt->scheduled?
> We should rename pending_intr_nr to pending_intr(boolean).

It's not clear to me that the old logic around pt->pending_intr_nr and
pt->scheduled really needs to change that drastically. The more we mess with
this code the more likely we are to break stuff, as it's hard to get good
coverage of the timer_modes and various ways guest Oses may manage their
timers.

I would prefer to see whether moving the update of pt->scheduled out of
pt_intr_post() and back into the timer_fn() works. That moves us back
towards what we had before your patches, and therefore I'm more comfortable
with it.

 -- Keir



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