Re: [PATCH 09/15] x86, amd: add accessor for number of cores per compute unit

From: Guenter Roeck
Date: Mon Aug 31 2015 - 09:54:11 EST

On 08/31/2015 06:38 AM, Peter Zijlstra wrote:
On Mon, Aug 31, 2015 at 06:26:00AM -0700, Guenter Roeck wrote:
On 08/31/2015 01:38 AM, Peter Zijlstra wrote:
On Sun, Aug 30, 2015 at 05:53:22PM +0200, Borislav Petkov wrote:
On Sat, Aug 29, 2015 at 11:19:14AM +0200, Ingo Molnar wrote:
So let me withdraw my ack: the much more important question that I
missed first time around, why is this reporting feature living in
hwmon, not in perf? We have energy reporting facilities in perf that
this should be synced to.

Because there's already fam15h_power driver which is exactly for that.
Making it part of perf is then a question of cat-ting the same sysfs
file twice, at the beginning and at the end of the trace, which is

That don't make sense.

Looking at the BKDG Fam 15h 60h-6Fh these MSRs are per compute unit.
This means you can do much finer grained measurements than system wide
-- which is all hwmon seems capable of.

Is it ? Why ?

Dunno, because there's that big old loop iterating all cpus?

What does that have to do with 'hwmon' ? The current implementation in the
driver may not be a good idea, and maybe for good reasons; I can not
comment on that. However, you concluded from that implementation that
hwmon, the subsystem, would not be able to support 'much finer grained
measurements than system wide'. I would like to understand how you reached
that conclusion.


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