On 01/22/2014 07:02 AM, Michael Ellerman wrote:

On Thu, 2014-01-16 at 15:53 -0800, Cody P Schafer wrote:

quoted

These patches add basic pmus for 2 powerpc hypervisor interfaces to obtain
performance counters: gpci ("get performance counter info") and 24x7.

The counters supplied by these interfaces are continually counting and never
need to be (and cannot be) disabled or enabled. They additionally do not
generate any interrupts. This makes them in some regards similar to software
counters, and as a result their implimentation shares some common code (which
an initial patch exposes) with the sw counters.

Hi Cody,

Can you please add some more explanation of this series.

In particular why do we need two new PMUs, and how do they relate to each
other?

And can you add an example of how I'd actually use them using perf.

Yeah, agreed.