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Re: [Xen-devel] [PATCH] Xenoprof patches for xen-unstable

Santos, Jose Renato G wrote:

You are welcome. Please keep me posted on how you are using it and any insights you may get using xenoprof


 Current known limitation/bugs are
  - No support for SMP guests yet.
  - when using passive domains, most samples are lost.

Thanks for the explanation below.  Speaking for myself, neither
of the above will be an issue, since we can run oprofile
on all the kernels and are not yet running SMP guests.

Many thanks!


Excuse my ignorance - what exactly is a passive domain?

  Sorry for using the term without explanation.
  We call passive domains domains that are
  profiled but do not have support for collecting PC samples
  (i.e they do not have oprofile running).
  In this case their samples are sent to the initiator
  domain (usually domain 0) which process the samples on
  their behalf. In this case the samples
  are not decoded to specific binary files/functions
  but are assigned to the whole domain (coarse granularity
  profiling). We are planning to enable fine granularity
profiling for the kernel code on passive domains in the future. However, as I mentioned, xenoprof is not working properly with passive domains yet.

  In the normal mode of operation that is functional
  at this time, every domain being profiled must be running
  an oprofile kernel module to process the PC samples
generated when they are running. Each domain will have a partial report of the samples that happened when they were running.
  System wide profiling is obtained by combining the
  reports of all profiled domains.
I hope this is clearer now.


 I will be working on these issues and post new patches
 when I have them available.



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