From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
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
Subject: Re: [PATCH v3] x86,sched: allow topologies where NUMA nodes share an LLC
Date: Thu, 29 Mar 2018 15:57:02 +0200 [thread overview]
Message-ID: <20180329135702.GB4043@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <aa369ee2-6557-8e3f-e2b4-d347b27825a6@linux.intel.com>
On Thu, Mar 29, 2018 at 06:45:12AM -0700, Dave Hansen wrote:
> On 03/29/2018 06:16 AM, Thomas Gleixner wrote:
> >> This is OK at least on the hardware we are immediately concerned about
> >> because the LLC sharing happens at both the slice and at the package
> >> level, which are also NUMA boundaries.
> > So that addresses the scheduler interaction, but it still leaves the
> > information in the sysfs files unchanged. See cpu/intel_cacheinfo.c. There
> > are applications which use that information so it should be correct.
>
> Were you thinking of shared_cpu_list/map?
Yes, the fact that those are changed and the Changelog doesn't mention
them is a giant fail all by itself.
> The information in there is
> correct for core->off-package access. It is not correct for
> core->on-package access, unless that access is perfectly interleaved
> across both package "slices".
The fact that 'simple' measures like cache/cpu are now completely broken
is a problem.
next prev parent reply other threads:[~2018-03-29 13:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-29 0:00 [PATCH v3] x86,sched: allow topologies where NUMA nodes share an LLC Alison Schofield
2018-03-29 13:16 ` Thomas Gleixner
2018-03-29 13:45 ` Dave Hansen
2018-03-29 13:57 ` Peter Zijlstra [this message]
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
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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