RE: [Xen-devel] Revisiting the Xenoprof problem

["Venkataraman, Meenakshi" <meenakshi.venkataraman@xxxxxxxxx>]

In answer to your questions...

> Are you able to profile dom0 alone?
>I suggest that you try this first.

I tried what you suggest above, I'm not able to do it without tweaking
the kernel. I found that I was unable to get any samples from opcontrol
for even just domain 0. The problem is that oprofile thinks that it is
on a P-III CPU, while it is actually running on a core 2.

If I fake the events and bitmasks to appear as if they're for an
i386/P-III but actually put the events and bitmasks for a core 2,
opcontrol works for the CPU_CLK_UNHALTED event. I haven't tested with
other events. Opreport is still not working.

The problem is traceable to the hypervisor, which is the entity that
determines the cpu_type during bootup. I'm trying to figure out why the
hypervisor is behaving strangely.

Has anyone come across such a problem?

>Then try using passive domain profiing which enables guest profiling
but >does not require running oprofile in domU. It is much simpler and
easier to >use. Take a look at
http://www.xen.org/files/summit_3/xenoprof_tutorial.pdf >for a xenoprof
tutorial. It is a little old but it should be usefull >(mostly the xen
and oprofile versions have changed since then; otherwise >everything
still applies)

I'll take a look at the tutorial you point to.

Thanks a ton,
Meenakshi


-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Santos, Jose
Renato G
Sent: Wednesday, November 14, 2007 11:32 PM
To: Venkataraman, Meenakshi; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel] Revisiting the Xenoprof problem

Are you able to profile dom0 alone?
I suggest that you try this first.
Then try using passive domain profiing which enables guest profiling but
does not require running oprofile in domU. It is much simpler and easier
to use. Take a look at
http://www.xen.org/files/summit_3/xenoprof_tutorial.pdf for a xenoprof
tutorial. It is a little old but it should be usefull (mostly the xen
and oprofile versions have changed since then; otherwise everything
still applies)

Renato

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Venkataraman, Meenakshi
> Sent: Wednesday, November 14, 2007 9:32 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] Revisiting the Xenoprof problem
>
> Hi all,
>
> There was a discussion previously on oprofile not working in Dom U.
> Oprofile prints the following message and exits.
>
> -------- snip -----------
>
> Using default event: CPU_CLK_UNHALTED:100000:0:1:1 Using 2.6+
> OProfile kernel interface.
> Reading module info.
> Failed to open profile device: Operation not permitted
> Couldn't start oprofiled.
> Check the log file "/var/lib/oprofile/oprofiled.log" and kernel syslog
>
> -------- snip -----------
>
> There was an email exchange a year ago on the same problem. (see here:
> http://lists.xensource.com/archives/html/xen-devel/2006-05/msg
01168.html
> )
>
>
> I've followed the sequence of steps mentioned in the thread,
> and yet I get the same problem. I'm starting the daemon in
> Dom0 before I start oprofile in the guest.
>
> Thoughts and/or solutions, anyone?
>
> Thanks in advance!
> Meenakshi
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>

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