Re: [PATCH] Xenoprof patches for xen-unstable

[Nivedita Singhvi <niv@us.ibm.com>]

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

Absolutely!

>>>>  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!

Nivedita


>>>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.
> 
>   Renato
> 
> 
>>>>  I will be working on these issues and post new patches
>>>>  when I have them available.
>>>
>>>thanks!
>>>
>>>Nivedita
>>>
>>>
>>>
>>>
> 
> 
>