Re: [Xen-devel] Re: Getting the page fault count for domU

[Tim Deegan <tim@xxxxxxx>]

At 06:37 -0700 on 03 Oct (1317623870), Chintamani Siddeshwar wrote:
> I am interested in counting the number of page-faults in the guest -
> page-faults that result in a disk I/O.

You will have to do that from inside the guest - only the guest's OS
knows which of its page-faults result in I/O, and on modern (EPT/RVI)
hardware, Xen doesn't even see most guest page-faults.

> Also when would XEN tools page a guest memory to disk? Is it a manual
> process (by running "xenpaging" command) or is it a performance enhancement
> added in recent versions of XEN?

Only when the xenpaging daemon is running.  It is definitely not a
performance enhancement (memory pressure is better dealt with by the
guest) but is useful as a backstop if you're overcommitting memory some
other way.

Tim.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel