linux-kernel - Re: [Xen-devel] [PATCH] xen/evtchn: Handle VIRQ_TIMER before any other hardirq in event loop.

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Date:	Tue, 2 Apr 2013 15:53:13 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xensource.com>,
	Keir Fraser <keir.fraser@...rix.com>
Subject: Re: [Xen-devel] [PATCH] xen/evtchn: Handle VIRQ_TIMER before any
 other hardirq in event loop.

On 01/04/13 15:07, Konrad Rzeszutek Wilk wrote:
> From: Keir Fraser <keir.fraser@...rix.com>
> 
> This avoids any other hardirq handler seeing a very stale jiffies
> value immediately after wakeup from a long idle period. The one
> observable symptom of this was a USB keyboard, with software keyboard
> repeat, which would always repeat a key immediately that it was
> pressed. This is due to the key press waking the guest, the key
> handler immediately runs, sees an old jiffies value, and then that
> jiffies value significantly updated, before the key is unpressed.

It's a bit of hack but what else can you do when there is no generic
mechanism to have different event priorities.

Reviewed-by: David Vrabel <david.vrabel@...rix.com>

The subject should be prefixed with: "xen/events" as this isn't a patch
to the evtchn driver.

David
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