linux-kernel - Re: [PATCH 1/2] x86/CPU/AMD: Present package as die instead of socket

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Message-ID: <20170627161156.yim2pxtyg7efrbef@pd.tnic>
Date:   Tue, 27 Jun 2017 18:11:56 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Duran, Leo" <leo.duran@....com>
Cc:     'Thomas Gleixner' <tglx@...utronix.de>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 1/2] x86/CPU/AMD: Present package as die instead of socket

On Tue, Jun 27, 2017 at 03:48:55PM +0000, Duran, Leo wrote:
> Basically, in our case a Package may contain more than one L3 (i.e.,
> in hardware terms, there may more than one 'Core complex' in a 'Die').
> The important point is that all logical processors (threads) that
> share an L3 have a common "cpu_llc_id".

All that means nothing if it doesn't have any effect on scheduling.

If moving the working set between L3s within the package, as you call
it, is not measureable, i.e., task migration, then we don't care. The
whole exercise is not about modelling the hardware topology accurately
but for presenting sufficient detailed topology to the scheduler so that
it works optimally on Zen.

-- 
Regards/Gruss,
    Boris.

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