Re: [PATCH 0/8] Add support for PowerPC Hypervisor supplied performancecounters

From: Anshuman Khandual
Date: Wed Jan 22 2014 - 04:38:57 EST

On 01/22/2014 07:02 AM, Michael Ellerman wrote:
> On Thu, 2014-01-16 at 15:53 -0800, Cody P Schafer wrote:
>> 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.

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