Re: open/stat64 syscalls run faster on Xen VM than standard Linux

[xuehai zhang <hai@cs.uchicago.edu>]

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