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: Mon, 13 Jan 2020 13:22:14 +0000 [thread overview]
Message-ID: <20200113132214.GD10914@e105550-lin.cambridge.arm.com> (raw)
In-Reply-To: <f973e77b-9c0a-6506-da97-f7a0ea1829fd@arm.com>
On Sun, Jan 12, 2020 at 01:22:02PM +0000, Valentin Schneider wrote:
> On 09/01/2020 10:52, Morten Rasmussen wrote:
> >> 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.
> >
>
> Right, the point I was trying to make is that node boundaries can be pretty
> much anything, so nodes can span over LLCs, or LLCs can span over nodes,
> which is why we need checks such as the one in arch_topology() that lets us
> build up a usable domain hierarchy (which cares about LLCs, at least at some
> level).
Indeed. The topology masks can't always be used as is to define the
sched_domain hierarchy.
next prev parent reply other threads:[~2020-01-13 13:22 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
2020-01-12 13:22 ` Valentin Schneider
2020-01-13 13:22 ` Morten Rasmussen [this message]
2020-01-02 13:59 ` Sudeep Holla
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