linux-kernel - Re: [PATCH v2 0/5] Cavium ThunderX uncore PMU support

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Message-ID: <20160628140459.GA27541@hardcore>
Date:	Tue, 28 Jun 2016 16:04:59 +0200
From:	Jan Glauber <jan.glauber@...iumnetworks.com>
To:	Will Deacon <will.deacon@....com>
CC:	Mark Rutland <mark.rutland@....com>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 0/5] Cavium ThunderX uncore PMU support

On Tue, Jun 28, 2016 at 11:24:20AM +0100, Will Deacon wrote:
> Hi Jan,
> 
> On Wed, Mar 09, 2016 at 05:21:02PM +0100, Jan Glauber wrote:
> > This patch series provides access to various counters on the ThunderX SOC.
> > 
> > For details of the uncore implementation see patch #1.
> > 
> > Patches #2-5 add the various ThunderX specific PMUs.
> > 
> > As suggested I've put the files under drivers/perf/uncore. I would
> > prefer this location over drivers/bus because not all of the uncore
> > drivers are bus related.
> 
> What's the status of these patches? Were you planning to send a new
> version?
> 
> Will

Hi Will,

I was half-way through with addressing Mark's review comments when
got side-tracked.

The principle question these patches raised remains open though in my
opinion, how to determine the socket a device belongs to.

There is no first-class interface to ask a device or the firmware
which socket the device lives on.

The options I see are:
A) Using NUMA node information, depends on CONFIG_NUMA
B) Decoding the socket bits of the PCI BAR address
C) Using PCI topology information

A is what I tried, but I agree that depending on CONFIG_NUMA is not a good
solution. B would be easy but looks not very future-proof. So option C
is what is left...

thanks,
Jan