RE: [Xen-devel] profiling active RHEL 4 PV domains with xenoprof

["Santos, Jose Renato G" <joserenato.santos@xxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Andrew Evans
> Sent: Thursday, January 28, 2010 5:38 PM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] profiling active RHEL 4 PV domains with xenoprof
> 
> Hi,
> 
> Is it necessary to run a xenoprof-patched oprofile in a PV 
> domU being actively profiled? I ask because

   Yes, you need need xenoprof support both in the kernel and in the OProfile 
user level tools in anctive profiled domain.
> 
> http://xenoprof.sourceforge.net/xenoprof_2.0.txt
> 
> seems to say no (no mention of --xen switch) but
> 
> http://www.xen.org/files/summit_3/xenoprof_tutorial.pdf
> 
> seems to say yes (specifies use of --xen in domUs). I'm 
> running RHEL 4 in the domU I want to actively profile, and 
> RHEL 4 provides the ancient
> oprofile-0.8.1 package, with no support for the --xen switch. 
> I've gotten oprofile 0.9.6 with xenoprof patches built on


  Are you sure Oprofile user level tools has xenoprof support?
  The latest patch avaialable in http://xenoprof.sourceforge.net/ is for 
oprofile 0.9.5 but you claim to be using 0.9.6
  Try using 0.9.5 and apply the patch.

> RHEL 4 but haven't been able to test it due to XENOPROF_start 
> failing (see other message).
> 

> Another thing I'm confused about: the above xenoprof tutorial 
> also specifies use of the --event switch in domUs, saying 
> they must use the same event as dom0. Makes sense, but my 
> domUs are PV, and oprofile says only timer interrupts are 
> usable. So must I also use timer interrupts on dom0?
> 

  No, you should use the same event in dom0 and domU and not timer mode.
  If Oprofile is reporting timer mode in domU there is something wrong in its 
OProfile configuration; either you don't have the right patches or you are not 
correctly synchronyzing dom0 and domU opcontrol commands.


  Renato
 
> thanks,
> 
> -Andrew
> 
> 
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