Re: [Xen-devel] open/stat64 syscalls run faster on Xen VM than standard Linux

[xuehai zhang <hai@xxxxxxxxxxxxxxx>]

Petersson, Mats wrote:
>  
>
> > -----Original Message-----
> > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> > [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] 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

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