From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nek1O-00047b-D2 for qemu-devel@nongnu.org; Tue, 09 Feb 2010 01:56:30 -0500 Received: from [199.232.76.173] (port=59884 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nek1N-00047L-JC for qemu-devel@nongnu.org; Tue, 09 Feb 2010 01:56:29 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Nek1L-0004Py-0C for qemu-devel@nongnu.org; Tue, 09 Feb 2010 01:56:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50711) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Nek1K-0004Pk-Gc for qemu-devel@nongnu.org; Tue, 09 Feb 2010 01:56:26 -0500 Message-ID: <4B710714.1020109@redhat.com> Date: Tue, 09 Feb 2010 08:56:20 +0200 From: Avi Kivity MIME-Version: 1.0 References: <20100209012851.GJ25751@x200.localdomain> In-Reply-To: <20100209012851.GJ25751@x200.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: KVM call agenda for Feb 9 List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chris Wright Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org On 02/09/2010 03:28 AM, Chris Wright wrote: > Please send in any agenda items you are interested in covering. > hpet overhead on large smp guests I measured hpet consuming about a half a core's worth of cpu on an idle Windows 2008 R2 64-way guest. This is mostly due to futex contention, likely from the qemu mutex. Options: - ignore, this is about 1% of the entire system (but overhead might increase greatly if a workload triggers more hpet accesses) - push hpet into kernel, with virtio-net, virtio-blk, and kernel-hpet, there's little reason to exit into qemu - rcuify/fine-grain qemu locks -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.