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From: Morten Rasmussen <morten.rasmussen@arm.com>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: "Zengtao (B)" <prime.zeng@hisilicon.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Linuxarm <linuxarm@huawei.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cpu-topology: warn if NUMA configurations conflicts with lower layer
Date: Thu, 9 Jan 2020 10:52:28 +0000	[thread overview]
Message-ID: <20200109105228.GB10914@e105550-lin.cambridge.arm.com> (raw)
In-Reply-To: <c43342d0-7e4d-3be0-0fe1-8d802b0d7065@arm.com>

On Thu, Jan 02, 2020 at 01:22:19PM +0000, Valentin Schneider wrote:
> On 02/01/2020 12:47, Zengtao (B) wrote:
> >>
> >> As I said, wrong configurations need to be detected when generating
> >> DT/ACPI if possible. The above will print warning on systems with NUMA
> >> within package.
> >>
> >> NUMA:  0-7, 8-15
> >> core_siblings:   0-15
> >>
> >> The above is the example where the die has 16 CPUs and 2 NUMA nodes
> >> within a package, your change throws error to the above config which is
> >> wrong.
> >>
> > From your example, the core 7 and core 8 has got different LLC but the same Low
> > Level cache?
> 
> AFAIA what matters here is memory controllers, less so LLCs. Cores within
> a single die could have private LLCs and separate memory controllers, or
> shared LLC and separate memory controllers.

Don't confuse cache boundaries, packages and nodes :-)

core_siblings are cpus in the same package and doesn't say anything
about cache boundaries. It is not given that there is sched_domain that
matches the core_sibling span.

The MC sched_domain is supposed to match the LLC span which might
different for core_siblings. So the about example should be valid for a
NUMA-in-package system with one package containing two nodes.

Morten

  parent reply	other threads:[~2020-01-09 10:52 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-23  8:16 [PATCH] cpu-topology: warn if NUMA configurations conflicts with lower layer z00214469
2019-12-31 16:40 ` Sudeep Holla
2020-01-02  3:05   ` Zengtao (B)
2020-01-02 11:29     ` Sudeep Holla
2020-01-02 12:47       ` Zengtao (B)
2020-01-02 13:22         ` Valentin Schneider
2020-01-02 19:30           ` Dietmar Eggemann
2020-01-03  4:24           ` Zengtao (B)
2020-01-03 10:57             ` Valentin Schneider
2020-01-03 12:14               ` Valentin Schneider
2020-01-03 17:20                 ` Dietmar Eggemann
2020-01-06  1:48                   ` Zengtao (B)
2020-01-06 14:31                     ` Dietmar Eggemann
2020-01-08  2:19                       ` Zengtao (B)
2020-01-09 11:05                       ` Morten Rasmussen
2020-01-09 12:07                         ` Dietmar Eggemann
2020-01-06  1:52                 ` Zengtao (B)
2020-01-03 11:40             ` Sudeep Holla
2020-01-06  1:37               ` Zengtao (B)
2020-01-09 10:43                 ` Morten Rasmussen
2020-01-09 12:58                   ` Zengtao (B)
2020-01-11 20:56                     ` Valentin Schneider
2020-01-13  6:51                       ` Zengtao (B)
2020-01-13 11:16                         ` Valentin Schneider
2020-01-13 12:08                           ` Zengtao (B)
2020-01-13 12:22                             ` Dietmar Eggemann
2020-01-13 14:49                       ` Dietmar Eggemann
2020-01-13 15:15                         ` Valentin Schneider
2020-01-09 10:52           ` Morten Rasmussen [this message]
2020-01-12 13:22             ` Valentin Schneider
2020-01-13 13:22               ` Morten Rasmussen
2020-01-02 13:59         ` Sudeep Holla

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