From: Matthew Wilcox <willy@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
Michal Hocko <mhocko@kernel.org>,
linux-kernel@vger.kernel.org, "Anaczkowski,
Lukasz" <lukasz.anaczkowski@intel.com>,
"Box, David E" <david.e.box@intel.com>,
"Kogut, Jaroslaw" <Jaroslaw.Kogut@intel.com>,
"Koss, Marcin" <marcin.koss@intel.com>,
"Koziej, Artur" <artur.koziej@intel.com>,
"Lahtinen, Joonas" <joonas.lahtinen@intel.com>,
"Moore, Robert" <robert.moore@intel.com>,
"Nachimuthu, Murugasamy" <murugasamy.nachimuthu@intel.com>,
"Odzioba, Lukasz" <lukasz.odzioba@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Schmauss, Erik" <erik.schmauss@intel.com>,
"Verma, Vishal L" <vishal.l.verma@intel.com>,
"Zheng, Lv" <lv.zheng@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <bsingharora@gmail.com>,
Brice Goglin <brice.goglin@gmail.com>,
Dan Williams <dan.j.williams@intel.com>,
Jerome Glisse <jglisse@redhat.com>,
John Hubbard <jhubbard@nvidia.com>, Len Brown <lenb@kernel.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
devel@acpica.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, linux-api@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT
Date: Wed, 20 Dec 2017 13:16:49 -0800 [thread overview]
Message-ID: <20171220211649.GA32200@bombadil.infradead.org> (raw)
In-Reply-To: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com>
On Wed, Dec 20, 2017 at 12:22:21PM -0800, Dave Hansen wrote:
> On 12/20/2017 10:19 AM, Matthew Wilcox wrote:
> > I don't know what the right interface is, but my laptop has a set of
> > /sys/devices/system/memory/memoryN/ directories. Perhaps this is the
> > right place to expose write_bw (etc).
>
> Those directories are already too redundant and wasteful. I think we'd
> really rather not add to them. In addition, it's technically possible
> to have a memory section span NUMA nodes and have different performance
> properties, which make it impossible to represent there.
>
> In any case, ACPI PXM's (Proximity Domains) are guaranteed to have
> uniform performance properties in the HMAT, and we just so happen to
> always create one NUMA node per PXM. So, NUMA nodes really are a good fit.
I think you're missing my larger point which is that I don't think this
should be exposed to userspace as an ACPI feature. Because if you do,
then it'll also be exposed to userspace as an openfirmware feature.
And sooner or later a devicetree feature. And then writing a portable
program becomes an exercise in suffering.
So, what's the right place in sysfs that isn't tied to ACPI? A new
directory or set of directories under /sys/devices/system/memory/ ?
next prev parent reply other threads:[~2017-12-20 21:16 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 [this message]
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
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