From mboxrd@z Thu Jan 1 00:00:00 1970 From: xuehai zhang Subject: Re: open/stat64 syscalls run faster on Xen VM than standard Linux Date: Mon, 28 Nov 2005 08:47:31 -0600 Message-ID: <438B1883.1090805@cs.uchicago.edu> References: <907625E08839C4409CE5768403633E0B0EAAC3@sefsexmb1.amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <907625E08839C4409CE5768403633E0B0EAAC3@sefsexmb1.amd.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Petersson, Mats" Cc: Xen Mailing List List-Id: xen-devel@lists.xenproject.org Petersson, Mats wrote: > > > >>-----Original Message----- >>From: xen-devel-bounces@lists.xensource.com >>[mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of >>xuehai zhang >>Sent: 28 November 2005 08:21 >>To: Xen Mailing List >>Subject: [Xen-devel] open/stat64 syscalls run faster on Xen >>VM than standard Linux >> >>Dear all, >>When I debugged the execution performance of an application >>using strace, I found there are some system calls like open >>and stat64 which run faster on XenLinux than the standard >>Linux. The following is the output of running "strace -c >>/bin/sh -c /bin/echo foo" on both systems. An open call runs >>averagely 109 usec on standard Linux but only 41 usecs on >>XenLinux. An stat64 call runs >>75 usecs on standard Linux but only 19 usecs on XenLinux. >>The Xen VM runs on the same physical machine as the standard >>Linux. It uses loopback files in dom0 as the backends of VBDs. >>Any insight is highly appreciated. > > > And are you using the same Loopback file-system when running native > Linux? If not, it's probably the main cause of the difference. No, the native Linux runs on a regular linux machine and use the raw hard disk partitions. Xuehai