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Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT
To: Matthew Wilcox <willy@infradead.org>,
        Ross Zwisler <ross.zwisler@linux.intel.com>
References: <20171214021019.13579-1-ross.zwisler@linux.intel.com>
 <20171214130032.GK16951@dhcp22.suse.cz>
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Cc: Michal Hocko <mhocko@kernel.org>, linux-kernel@vger.kernel.org,
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From: Dave Hansen <dave.hansen@intel.com>
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Date: Wed, 20 Dec 2017 12:22:21 -0800
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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.