linux-kernel - RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file system

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Message-ID: <alpine.DEB.2.20.1610180121300.6407@nanos>
Date:   Tue, 18 Oct 2016 01:25:59 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Luck, Tony" <tony.luck@...el.com>
cc:     "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Anvin, H Peter" <h.peter.anvin@...el.com>,
        Ingo Molnar <mingo@...e.hu>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        Borislav Petkov <bp@...e.de>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        Nilay Vaish <nilayvaish@...il.com>, Shaohua Li <shli@...com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: RE: [PATCH v4 13/18] x86/intel_rdt: Add mkdir to resctrl file
 system

On Mon, 17 Oct 2016, Luck, Tony wrote:

> > How so? CLOSID 9 is using CLOSID 1 L2 settings. Are we just keeping the L2
> > setting of CLOSID 1 around and do not reset it to default?
> 
> No. When CLOSID 9 arrives at the L2 h/w, it doesn't just take the bits it
> likes an discard the high bits to map to L2_CBM[1]. It just turns into 
> into the maximum allowed value for an L2 CBM.

So all CLOSIDs >= 8 will use all valid CBM bits for L2? That's even more
insane as this breaks any L2 partitioning which is set up by CLOSIDs < 8.

So effectively CLOSIDs >= 8 are useless in the L3=16 and L2=8 case.

Thanks,

	tglx