lkml.org 
[lkml]   [2017]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 0/3] create sysfs representation of ACPI HMAT
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/ ?

\
 
 \ /
  Last update: 2017-12-20 22:17    [W:0.147 / U:3.856 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site