Re: [PATCH 0/3] powerpc: Instrument Hypervisor Calls

On Saturday 15 July 2006 17:30, Anton Blanchard wrote:

quoted

What happened to the question whether to use PURR values for also measuring
cycles spent executing the hcall as opposed to cycles that passed before
the hcall returns. Did that turn out not giving extra information after all
or was there a different reason to drop that idea?

You have to be careful with PURR since it may be context switched
between partitions.

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.

	Arnd <><