[PATCH 0/3] powerpc: Instrument Hypervisor Calls

[Luke Browning]

linuxppc-dev-bounces+lukebrowning=us.ibm.com at ozlabs.org wrote on 
07/15/2006 07:07:58 PM:

> 
> > Not sure I follow you. I would expect the PURR value to be restored 
after
> > a context switch, even if we continue on a different physical CPU.
> > 
> > The idea behind monitoring both PURR and timebase is that the 
difference
> > between the two tells you how long the partition was suspended during
> > the hcall.
> 
> Sounds good, last time I looked at the patch I thought it was gathering
> the PURR only. That on its own would make for some confusing results.
>

It would be more efficient to have a separate trace log for PHYP 
dispatches as 
there are many more hypervisor calls than PHYP dispatches.  I believe PHYP 
provides
a trace records for dispatches, which could be seperately written.  Perf 
tools can 
assemble the information from multiple records.  It would be nice to have 
processor
specific time function that reads either PURR or TB based on the platform.

Luke

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