From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Chmielewski Subject: Re: strange guest slowness after some time Date: Mon, 06 Apr 2009 17:19:17 +0200 Message-ID: <49DA1D75.6000604@wpkg.org> References: <49B29705.6000904@wpkg.org> <49B4E7A6.3090601@redhat.com> <49B4EDC9.9020504@wpkg.org> <49B4EE8F.7050001@redhat.com> <49BD007C.9030809@wpkg.org> <49BF7FB6.9080503@wpkg.org> <49BF8686.5050707@redhat.com> <49BF88BE.7040805@wpkg.org> <49BFC276.1080600@gmx.net> <49BFC53D.3020809@wpkg.org> <49BFD752.9050706@gmx.net> <49D1D950.7040809@wpkg.org> <49D2EBF2.1070706@cisco.com> <49D30801.5020201@wpkg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Felix Leimbach , avi@redhat.com, kvm@vger.kernel.org, Rusty Russell , Anthony Liguori To: "David S. Ahern" Return-path: Received: from mx03.syneticon.net ([78.111.66.105]:39843 "EHLO mx03.syneticon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452AbZDFPTX (ORCPT ); Mon, 6 Apr 2009 11:19:23 -0400 In-Reply-To: <49D30801.5020201@wpkg.org> Sender: kvm-owner@vger.kernel.org List-ID: Tomasz Chmielewski schrieb: > As I mentioned, it was using virtio net. > > Guests running with e1000 (and virtio_blk) don't have this problem. Also, virtio_console seem to be affected by this "slowness" issue. Am I correct to think that if: * on guest "lsmod" outputs: virtio_console 6828 0 [permanent] * on guest, /etc/inittab contains: 6:2345:respawn:/sbin/mingetty ttyS0 * on host, I start the guest with a parameter: -serial unix:/var/run/qemu-server/103.serial,server,nowait That the guests's ttyS0 console is "virtio_console"? If my thinking is correct, than I have a "slow serial console" on some of the guests using virtio_pci and virtio_console driver. By "slow serial console" I mean any character typed shows up after a second or so. It can be also "cured" like with virtio_net - just run: dd if=/dev/vda of=/dev/null And the console reacts normally. Stop dd, console is slow again. I have this issue on two guests with e1000 network, which use virtio_blk (and virtio_console...). I never saw this issue with guests which don't use virtio. -- Tomasz Chmielewski http://wpkg.org