From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: poor I/O performance on domU Date: Thu, 13 Jan 2005 11:00:52 -0600 Message-ID: <1105635651.25281.2.camel@localhost> References: <41E69C98.7090804@fzu.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <41E69C98.7090804@fzu.cz> Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Jan =?ISO-8859-1?Q?Kundr=E1t?= Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On Thu, 2005-01-13 at 10:06, Jan Kundr=E1t wrote: > ttylinux's rootfs is exported from ext3 fs via loopback device, could i= t=20 > be the cause of troubles? I think that's a reasonable answer. It should be easy to test though.=20 Try your same test on dom0 and use /dev/loopN where N is the loopback device that has your rootfs on it. The difference between testing /dev/loopN access on dom0 and the virtual block device on domU should tell you the Xen-imposed performance penalty. I did a quick test on my system and there was a 50% slowdown using the loopback device doing your test so I imagine it's that. Regards, > -jkt --=20 Anthony Liguori Samba, Linux/Windows Interoperability Linux Technology Center (LTC) - IBM Austin E-mail: aliguori@us.ibm.com Phone: (512) 838-1208 Tie Line: 678-1208 ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt