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Subject: Re: [PATCH v3] x86,sched: allow topologies where NUMA nodes share an
 LLC
To: Peter Zijlstra <peterz@infradead.org>
References: <20180329000024.GA16648@alison-desk.jf.intel.com>
 <alpine.DEB.2.21.1803291505590.1477@nanos.tec.linutronix.de>
 <20180329134723.GA4043@hirez.programming.kicks-ass.net>
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Cc: Thomas Gleixner <tglx@linutronix.de>,
        Alison Schofield <alison.schofield@intel.com>,
        Ingo Molnar <mingo@kernel.org>, Tony Luck <tony.luck@intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        "H. Peter Anvin" <hpa@linux.intel.com>, Borislav Petkov <bp@alien8.de>,
        David Rientjes <rientjes@google.com>,
        Igor Mammedov <imammedo@redhat.com>,
        Prarit Bhargava <prarit@redhat.com>, brice.goglin@gmail.com,
        x86@kernel.org, linux-kernel@vger.kernel.org
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <224bbc83-125d-0507-92af-5b6b4af62834@linux.intel.com>
Date: Thu, 29 Mar 2018 09:25:21 -0700
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On 03/29/2018 09:09 AM, Peter Zijlstra wrote:
> On Thu, Mar 29, 2018 at 07:34:58AM -0700, Dave Hansen wrote:
>> What should we say, though?
>>
>>              /*
>> 	      * false means 'c' does not share the LLC of 'o'.
>> 	      * Note: this decision gets reflected all the way
>> 	      * out to userspace
>> 	      */
>>              return false;
> That works, I suppose. You might want to put in a refernce to wherever
> it is you shrink llc-size such that cache-per-cpu remains invariant.

Hmm, if we shrink llc-size by splitting it, do we also need to create a
unique "id" for each slice?