From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Chmielewski Subject: Re: strange guest slowness after some time Date: Tue, 17 Mar 2009 20:24:02 +0100 Message-ID: <49BFF8D2.5080000@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> <49BFC743.20000@redhat.com> <49BFCC04.9080402@wpkg.org> <49BFD84F.8050509@gmx.net> <49BFD999.503@redhat.com> <49BFE146.2090308@wpkg.org> <49BFF20D.6010303@wpkg.org> <49BFF45A.5070307@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Avi Kivity , kvm@vger.kernel.org To: Felix Leimbach Return-path: Received: from mx03.syneticon.net ([78.111.66.105]:58378 "EHLO mx03.syneticon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364AbZCQTYH (ORCPT ); Tue, 17 Mar 2009 15:24:07 -0400 In-Reply-To: <49BFF45A.5070307@gmx.net> Sender: kvm-owner@vger.kernel.org List-ID: Felix Leimbach schrieb: >> OK, another bug found. >> >> Set your MTU to 100. >> >> On two hosts, do: >> >> HOST1_MTU1500# dd if=/dev/zero | ssh manager@HOST2 dd of=/dev/null >> HOST2_MTU100# dd if=/dev/zero | ssh manager@HOST1 dd of=/dev/null >> >> HOST2 with MTU 100 will crash after 10-15 minutes (with packet count >> still not overflown). >> > Intersting. What are the packet counter at crash time (roughly)? > > My - currently running - test is: > > Guest 1 (Linux): > MTU 150 > # cat /dev/zero | nc 7777 > > Guest 2 (Windows 2003 Server): > MTU: 1500 > # nc -l -p 7777 > NUL > > My packet are currently at 63 million without a problem - yet. I have it running with MTU 1500. And one of the guests (the one which was crashing with MTU=100) froze. On a VNC console I can see: virtio_net virtio0: id 64 is not a head! BUG: soft lockup - CPU#0 stuck for 61s! [ssh:2265] And "soft lockup" is being printed periodically. VNC and serial console do not react to any key press. Guest do not react on ACPI events (shutdown). kvm/qemu process is using 100% CPU. See this screenshot: http://www1.wpkg.org/lockup.png Guest that locks up is running Debian Lenny with 2.6.26 kernel. Guest that does not lock up runs Mandriva 2009.0 with 2.6.27.x kernel. (data being transferred both side to/from each of these hosts). -- Tomasz Chmielewski http://wpkg.org