Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945931AbXBPKtN (ORCPT ); Fri, 16 Feb 2007 05:49:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1945945AbXBPKtN (ORCPT ); Fri, 16 Feb 2007 05:49:13 -0500 Received: from 207.47.60.150.static.nextweb.net ([207.47.60.150]:18805 "EHLO webmail.xensource.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1945931AbXBPKtM (ORCPT ); Fri, 16 Feb 2007 05:49:12 -0500 User-Agent: Microsoft-Entourage/11.2.5.060620 Date: Fri, 16 Feb 2007 10:49:10 +0000 Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disable unsupported config options. From: Keir Fraser To: Dan Hecht , Jeremy Fitzhardinge CC: Chris Wright , Andi Kleen , , Ian Pratt , , Andrew Morton , Message-ID: Thread-Topic: [patch 14/21] Xen-paravirt: Add XEN config options and disable unsupported config options. Thread-Index: AcdRuBayVUAG+r2rEduvqQAX8io7RQ== In-Reply-To: <45D56D5A.3000300@vmware.com> Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1071 Lines: 23 On 16/2/07 08:37, "Dan Hecht" wrote: > Hmm? I thought the periodic timer and one-shot timer both generate the > same VIRQ. So, how can you mask one without masking the other? > > The tickless idle works since the block hypercall disables the periodic > timer. But for dynticks (aka NO_HZ), you'll need to mask the periodic > timer (even for a running vcpu), while keeping the one-shot timer > unmasked. I don't think Xen provides an interface to do that. There's no interface for this right now, but we can easily add one in a backward compatible way. This also will not prevent a dyntick kernel from running on an older Xen -- the guest will then receive to many timer interrupts, but that should only be a performance concern fixable by upgrading the hypervisor component of the system. -- Keir - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/