From: Dave Hansen <dave.hansen@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: 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
Subject: Re: [PATCH v3] x86,sched: allow topologies where NUMA nodes share an LLC
Date: Thu, 29 Mar 2018 07:37:29 -0700 [thread overview]
Message-ID: <596dcb0c-5bbc-f3be-203b-571170ee8f11@linux.intel.com> (raw)
In-Reply-To: <20180329134723.GA4043@hirez.programming.kicks-ass.net>
On 03/29/2018 06:47 AM, Peter Zijlstra wrote:
> Further I think Dave argued that we should not change the llc-size,
> because while SNC presents a subset of the cache to local CPUs, for
> remote data the whole cache is still available, again something some
> applications might rely on.
BTW, I may have argued this in the past, but I don't think it's the best
thing to do.
If anything, we should optimize for the _users_ of this information: the
performance-sensitive ones who are digging up the cache topology. They
are also likely to be the most NUMA-affinitized and stay node-local with
much of their memory traffic. That would seem to point us in the
direction of enumerating two separate, half-sized LLCs "shared" only by
the slice when SNC mode is on.
That's what I've argued to the hardware folks lately, at least.
next prev parent reply other threads:[~2018-03-29 14:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-29 0:00 Alison Schofield
2018-03-29 13:16 ` Thomas Gleixner
2018-03-29 13:45 ` Dave Hansen
2018-03-29 13:57 ` Peter Zijlstra
2018-03-29 13:47 ` Peter Zijlstra
2018-03-29 14:34 ` Dave Hansen
2018-03-29 16:09 ` Peter Zijlstra
2018-03-29 16:25 ` Dave Hansen
2018-03-29 16:29 ` Luck, Tony
2018-03-29 14:37 ` Dave Hansen [this message]
2018-03-29 14:55 ` Peter Zijlstra
2018-03-30 3:20 ` kbuild test robot
2018-03-30 17:34 ` Alison Schofield
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