From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v3 0/7] RTC: New logic to emulate RTC Date: Wed, 14 Mar 2012 09:54:16 +0100 Message-ID: <4F605CB8.20200@redhat.com> References: <4F60581A.7000800@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "qemu-devel@nongnu.org" , Jan Kiszka , "kvm@vger.kernel.org" , "aliguori@us.ibm.com" , Marcelo Tosatti To: "Zhang, Yang Z" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:46986 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759332Ab2CNIy1 (ORCPT ); Wed, 14 Mar 2012 04:54:27 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Il 14/03/2012 09:52, Zhang, Yang Z ha scritto: >>>>> Is there any comments with the version 3? >>> >>> Can you explain why you dropped the logic to set the timer to the >>> next event? > Do you mean why I change the rtc logic? The reason is that: When a > guest is idle, the main activity inside qemu is the rtc update > timer(2 per second). In our experience(running 64 rhel6u1 guests), it > will decrease pkg C6 residency about 6%(6% means 2 watts in my box). > And normally, the guest will not use the update-end interrupt and > alarm. So there has no need to run a periodic timer when guest isn't > using it. No, why you're keeping roughly the same logic as current QEMU, instead of the more radical changes that were in v2. Paolo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:51820) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7jyZ-0001Nu-NH for qemu-devel@nongnu.org; Wed, 14 Mar 2012 04:54:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S7jyT-0007kf-Km for qemu-devel@nongnu.org; Wed, 14 Mar 2012 04:54:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2576) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7jyT-0007kJ-D3 for qemu-devel@nongnu.org; Wed, 14 Mar 2012 04:54:25 -0400 Message-ID: <4F605CB8.20200@redhat.com> Date: Wed, 14 Mar 2012 09:54:16 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <4F60581A.7000800@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 0/7] RTC: New logic to emulate RTC List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Zhang, Yang Z" Cc: "aliguori@us.ibm.com" , Marcelo Tosatti , Jan Kiszka , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" Il 14/03/2012 09:52, Zhang, Yang Z ha scritto: >>>>> Is there any comments with the version 3? >>> >>> Can you explain why you dropped the logic to set the timer to the >>> next event? > Do you mean why I change the rtc logic? The reason is that: When a > guest is idle, the main activity inside qemu is the rtc update > timer(2 per second). In our experience(running 64 rhel6u1 guests), it > will decrease pkg C6 residency about 6%(6% means 2 watts in my box). > And normally, the guest will not use the update-end interrupt and > alarm. So there has no need to run a periodic timer when guest isn't > using it. No, why you're keeping roughly the same logic as current QEMU, instead of the more radical changes that were in v2. Paolo