From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1FTMfN-0000wT-Vo for qemu-devel@nongnu.org; Tue, 11 Apr 2006 13:28:38 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1FTMfN-0000w0-3I for qemu-devel@nongnu.org; Tue, 11 Apr 2006 13:28:37 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1FTMfM-0000vx-UD for qemu-devel@nongnu.org; Tue, 11 Apr 2006 13:28:36 -0400 Received: from [65.74.133.6] (helo=mail.codesourcery.com) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.52) id 1FTMkH-0007l8-6m for qemu-devel@nongnu.org; Tue, 11 Apr 2006 13:33:41 -0400 From: Paul Brook Subject: Re: [Qemu-devel] Network Performance between Win Host and Linux Date: Tue, 11 Apr 2006 18:28:28 +0100 References: <6fe044190604111020h47108190x23983325567fb51c@mail.gmail.com> In-Reply-To: <6fe044190604111020h47108190x23983325567fb51c@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200604111828.29361.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On Tuesday 11 April 2006 18:20, Kenneth Duda wrote: > I am also having severe performance problems using NFS-over-TCP on > qemu-0.8 with a Linux host and guest. I will be looking at this > today. My current theory is that the whole machine is going idle > before qemu decides to poll kernel ring buffers holding packets the > guest is transmitting, but if anyone has actual information, please > let me know. You could be suffering from high interrupt latency. If the guest CPU is not idle then qemu only checks for interrupts (eg. the network RX interrupt) every 1ms or 1/host_HZ seconds, whichever is greater. If the guest CPU is idle it should respond immediately. I wouldn't be surprised if this problem is worse when using kqemu. Paul