Date: Wed, 8 Mar 2017 09:30:46 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Stephane Eranian <eranian@google.com>
cc: "Luck, Tony" <tony.luck@intel.com>,
        Vikas Shivappa <vikas.shivappa@linux.intel.com>,
        "Shivappa, Vikas" <vikas.shivappa@intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "hpa@zytor.com" <hpa@zytor.com>, "mingo@kernel.org" <mingo@kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        "Kleen, Andi" <andi.kleen@intel.com>,
        "davidcc@google.com" <davidcc@google.com>
Subject: Re: [PATCH 1/1] x86/cqm: Cqm requirements
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Stephane,

On Tue, 7 Mar 2017, Stephane Eranian wrote:
> On Tue, Mar 7, 2017 at 12:04 PM, Luck, Tony <tony.luck@intel.com> wrote:
> >> That's all nice and good, but I still have no coherent explanation why
> >> measuring across allocation domains makes sense.
> >
> > Is this in reaction to this one?
> >
> >>> 5)      Put multiple threads into a single measurement group
> >
> > If we fix it to say "threads from the same CAT group" does it fix things?
> >
> Inside a CAT partition, there may be multiple tasks split into different
> cgroups.  We need the ability to monitor groups of tasks individually
> within that CAT partition. I think this is what this bullet is about.

I completely understand that. That's fine and I never debated that one, but
the requirements list is too vague about what you want to measure.

> >>> 5)      Put multiple threads into a single measurement group

That can be:

     A) threads within a CAT group

     B) threads which belong to different CAT groups

A) is fine. B) does not make any sense to me

Same applies for per CPU measurements.

Thanks,

	tglx