From mboxrd@z Thu Jan  1 00:00:00 1970
From: Diego Ongaro <diego.ongaro@rice.edu>
Subject: Interrupts to dom0
Date: Tue, 10 Jul 2007 10:46:07 -0500
Message-ID: <4693A9BF.5070100@rice.edu>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xensource.com>
List-Unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

I'd like to understand the behavior of a guest domain receiving and 
answering a ping, while competing with other guest domains for the CPU.

Using xentrace, I've found that when an interrupt on the network 
interface comes in, the scheduler is pretty good about waking and 
scheduling the ping receiving domain next. However, once the ping 
receiving domain blocks, the scheduler often allows other guest domains 
to run before scheduling domain 0 again. Domain 0 is not woken and, 
thus, does not get its priority boosted.

My main question is whether domain-0 operates strictly by polling, 
rather than by virtual interrupts, in this scenario.

Thanks,
Diego Ongaro
Rice University