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

["Stephen C. Tweedie" <sct@xxxxxxxxxx>]

Hi,

On Mon, 2005-11-28 at 09:50 -0600, xuehai zhang wrote:

> I mounted the loopback file in dom0, chrooted to the mountpoint and redid the 
> experiment. The 
> results is attached below. The time of open and stat64 calls is similar to 
> the XenLinux case and 
> also much smaller than the standard Linux case. So, either using loopback 
> file as backend of 
> XenLinux or directly mounting it in local filesystem will result in some 
> benefit (maybe just caused 
> by the extra layer of block caching) for the performance of some system calls.

What time, exactly, is being measured here?  Is it wall-clock
gettimeofday?  Or only elapsed time inside the domU?  It would be
enlightening to re-measure the performance by counting the number of
times these operations can be completed in a second, just to get a
second opinion and to determine if the difference is genuine or if it's
just an artifact of how we're measuring time when multiple domains are
involved.

--Stephen



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