From: Michael Ellerman <mpe@ellerman•id.au>
To: Matthew Wilcox <willy@infradead•org>,
Ross Zwisler <ross.zwisler@linux•intel.com>
Cc: Michal Hocko <mhocko@kernel•org>, "Box\,
David E" <david.e.box@intel•com>,
Dave Hansen <dave.hansen@intel•com>, "Zheng\,
Lv" <lv.zheng@intel•com>, linux-nvdimm@lists•01.org, "Verma\,
Vishal L" <vishal.l.verma@intel•com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel•com>, "Anaczkowski\,
Lukasz" <lukasz.anaczkowski@intel•com>, "Moore\,
Robert" <robert.moore@intel•com>,
linux-acpi@vger•kernel.org, "Odzioba\,
Lukasz" <lukasz.odzioba@intel•com>, "Schmauss\,
Erik" <erik.schmauss@intel•com>, Len Brown <lenb@kernel•org>,
John Hubbard <jhubbard@nvidia•com>,
linuxppc-dev@lists•ozlabs.org, Jerome Glisse <jglisse@redhat•com>,
Dan Williams <dan.j.williams@intel•com>,
devel@acpica•org, "Kogut\, Jaroslaw" <Jaroslaw.Kogut@intel•com>,
linux-mm@kvack•org, "Koss\, Marcin" <marcin.koss@intel•com>,
linux-api@vger•kernel.org, Brice Goglin <brice.goglin@gmail•com>,
"Nachimuthu\, Murugasamy" <murugasamy.nachimuthu@intel•com>,
"Rafael J. Wysocki" <rjw@rjwysocki•net>,
linux-kernel@vger•kernel.org, "Koziej\,
Artur" <artur.koziej@intel•com>, "Lahtinen\,
Joonas" <joonas.lahtinen@intel•com>,
Andrew Morton <akpm@linux-foundation•org>,
Tim Chen <tim.c.chen@linux•intel.com>
Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT
Date: Thu, 21 Dec 2017 23:50:40 +1100 [thread overview]
Message-ID: <87mv2cfdnj.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171220181937.GB12236@bombadil.infradead.org>
Matthew Wilcox <willy@infradead•org> writes:
> On Mon, Dec 18, 2017 at 01:35:47PM -0700, Ross Zwisler wrote:
>> What I'm hoping to do with this series is to just provide a sysfs
>> representation of the HMAT so that applications can know which NUMA nodes to
>> select with existing utilities like numactl. This series does not currently
>> alter any kernel behavior, it only provides a sysfs interface.
>>
>> Say for example you had a system with some high bandwidth memory (HBM), and
>> you wanted to use it for a specific application. You could use the sysfs
>> representation of the HMAT to figure out which memory target held your HBM.
>> You could do this by looking at the local bandwidth values for the various
>> memory targets, so:
>>
>> # grep . /sys/devices/system/hmat/mem_tgt*/local_init/write_bw_MBps
>> /sys/devices/system/hmat/mem_tgt2/local_init/write_bw_MBps:81920
>> /sys/devices/system/hmat/mem_tgt3/local_init/write_bw_MBps:40960
>> /sys/devices/system/hmat/mem_tgt4/local_init/write_bw_MBps:40960
>> /sys/devices/system/hmat/mem_tgt5/local_init/write_bw_MBps:40960
>>
>> and look for the one that corresponds to your HBM speed. (These numbers are
>> made up, but you get the idea.)
>
> Presumably ACPI-based platforms will not be the only ones who have the
> ability to expose different bandwidth memories in the future. I think
> we need a platform-agnostic way ... right, PowerPC people?
Yes!
I don't have any detail at hand but will try and rustle something up.
cheers
prev parent reply other threads:[~2017-12-21 12:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171214021019.13579-1-ross.zwisler@linux.intel.com>
[not found] ` <20171214130032.GK16951@dhcp22.suse.cz>
[not found] ` <20171218203547.GA2366@linux.intel.com>
2017-12-20 18:19 ` [PATCH v3 0/3] create sysfs representation of ACPI HMAT Matthew Wilcox
2017-12-20 20:22 ` Dave Hansen
2017-12-20 21:16 ` Matthew Wilcox
2017-12-20 21:24 ` Ross Zwisler
2017-12-20 22:29 ` Dan Williams
2017-12-20 22:41 ` Ross Zwisler
2017-12-21 20:31 ` Brice Goglin
2017-12-22 22:53 ` Dan Williams
2017-12-22 23:22 ` Ross Zwisler
2017-12-22 23:57 ` Dan Williams
2017-12-23 1:14 ` Rafael J. Wysocki
2017-12-27 9:10 ` Brice Goglin
2017-12-30 6:58 ` Matthew Wilcox
2017-12-30 9:19 ` Brice Goglin
2017-12-20 21:13 ` Ross Zwisler
2017-12-21 1:41 ` Elliott, Robert (Persistent Memory)
2017-12-22 21:46 ` Ross Zwisler
2017-12-21 12:50 ` Michael Ellerman [this message]
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