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From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, tony.luck@intel.com,
	tim.c.chen@linux.intel.com, bp@alien8.de, rientjes@google.com,
	imammedo@redhat.com, torvalds@linux-foundation.org,
	prarit@redhat.com, toshi.kani@hp.com, brice.goglin@gmail.com,
	hpa@linux.intel.com, mingo@kernel.org
Subject: Re: [PATCH] x86, sched: allow topolgies where NUMA nodes share an LLC
Date: Thu, 8 Jun 2017 22:00:41 +0200	[thread overview]
Message-ID: <20170608200041.GB8337@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20170608193928.A3B5497F@viggo.jf.intel.com>

On Thu, Jun 08, 2017 at 12:39:28PM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> Our SMP boot code has a series of assumptions about what NUMA
> nodes are that are enforced via topology_sane().  Once upon a
> time, we verified that a CPU package only contained a single node
> (fixed in cebf15eb0).  Today, we verify that SMT siblings and
> LLCs do not span nodes.
> 
> The SMT siblings assumption is safe, but the LLC is violated on
> current hardware.

What does? That does sound broken. How can a cache domain sanely span
memory controllers?

This needs far more explanation.

  reply	other threads:[~2017-06-08 20:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-08 19:39 Dave Hansen
2017-06-08 20:00 ` Peter Zijlstra [this message]
2017-06-08 20:08   ` Luck, Tony
2017-06-08 20:20     ` Peter Zijlstra

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