linux-kernel - Re: [PATCH 1/1] x86/cqm: Cqm requirements

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Message-ID: <alpine.DEB.2.20.1703080927260.3521@nanos>
Date:   Wed, 8 Mar 2017 09:30:46 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Stephane Eranian <eranian@...gle.com>
cc:     "Luck, Tony" <tony.luck@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        "Shivappa, Vikas" <vikas.shivappa@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Kleen, Andi" <andi.kleen@...el.com>,
        "davidcc@...gle.com" <davidcc@...gle.com>
Subject: Re: [PATCH 1/1] x86/cqm: Cqm requirements

Stephane,

On Tue, 7 Mar 2017, Stephane Eranian wrote:
> On Tue, Mar 7, 2017 at 12:04 PM, Luck, Tony <tony.luck@...el.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