Re: [RFC PATCH 3/3 v3] perf: Update perf tool to monitor uncore events

[Andi Kleen <andi@firstfloor.org>]

On Tue, Dec 14, 2010 at 01:33:27PM +0100, Peter Zijlstra wrote:
> > > First of all, "uncore" is an x86-specific term and so it's not clear to 
> > > me if you meant for all arches to utilize this encoding for all "not 
> > > core but on the same die" events (IBM Power arch refers to this as 
> > > "nest" logic).
> 
> I don't think the x86 uncore matches the "not on core but on the same
> die" definition. The x86-uncore thing is more like a memory controller
> PMU (and since the memory controller is on die it is of course on die,

memory controller + interconnect + cache + power management + various other things.

Older x86 CPUs also had special PMUs on die for parts of that, but
without memory controller.

> but its not just any random on-die thing).
> 
> The wire-speed thing has tons of special purpose 'cores' on die, each of
> them having a PMU.

Modern x86 CPUs also have other PMUs, at least in package (e.g. in the 
GPU) 

> Using the sysfs stuff you could actually expose each individually.

I expect this will be also needed on x86. Also there are x86 SOCs
where other parts of the SOC will have their own counters too.
So in general a flexible scheme to describe that is useful.

-Andi