From: Keir Fraser <keir@xen.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: xen-devel@lists.xensource.com, Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH] xen: always handle VIRQ_TIMER first.
Date: Sat, 16 Oct 2010 08:14:07 +0100 [thread overview]
Message-ID: <C8DF0F4F.262B3%keir@xen.org> (raw)
In-Reply-To: <4CB8C393.4080809@goop.org>
On 15/10/2010 22:11, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote:
>> When guest resumes execution after a long period blocked, the unblocking
>> interrupt may be handled before the inevitable timer interrupt which
>
> Why "inevitable"? What if the next timer event is still some time in
> the future? Or are you assuming the timer is driven by the default Xen
> 100Hz timer?
Do you sometimes disable, or indeed never use, VCPUOP_set_periodic_timer?
Hmmm... Perhaps as you suggest this would be a generic issue with any
tickless kernel, and the correct upstream fix for issues such as USB kbd
repeat -- if indeed such issues still exist -- is to fix such hardirq
handlers to not depend on jiffies.
We fixed it the way we did in 'classic Xen' patched kernels since it seemed
arhitecturally neatest. I can accept that in the tickless kernel world that
may not actually be true.
-- Keir
next prev parent reply other threads:[~2010-10-16 7:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-15 10:52 [PATCH] xen: always handle VIRQ_TIMER first Ian Campbell
2010-10-15 17:18 ` Jeremy Fitzhardinge
2010-10-15 18:30 ` Keir Fraser
2010-10-15 21:11 ` Jeremy Fitzhardinge
2010-10-16 6:48 ` Ian Campbell
2010-10-16 7:14 ` Keir Fraser [this message]
2010-10-17 6:11 ` Jeremy Fitzhardinge
2010-10-17 7:38 ` Keir Fraser
2010-10-18 13:20 ` Jan Beulich
2010-10-18 16:52 ` Jeremy Fitzhardinge
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