Re: [RFC] activate performance counter registers on Netlogic XLR chip

[Jayachandran C. <jayachandranc@netlogicmicro.com>]

On Sat, Oct 01, 2011 at 02:18:49PM +0800, Hillf Danton wrote:
> On Netlogic XLR chip two pairs of performance counter registers,
> 
>    perf_ctrl0: c0 reg 25 sel 0, perf_cntr0: c0 reg 25 sel 1
>    perf_ctrl1: c0 reg 25 sel 2, perf_cntr0: c0 reg 25 sel 3
> 
> provide a means for software to count processor events.
> 
> At most 64 events can be counted, such as,
>    Instruction fetched and retired, branch instructions
>    Instruction and Data Cache Unit statistics
>    Instruction and Data TLB statistics
>    Instruction Fetch Unit statistics
>    Instruction Execution Unit statistics
>    Load/store Unit statistics
>    Cycle Count
> 
> They are activated based on the model of mips/74k, and
> any comment is appreciated.

I have not looked at 74k, but on XLR there is only one set of perf counter
registers in a core (or 4 hardware threads). These perf counters can count 
either the events on one thread or all of the threads put together.

JC.