Re: [RFC][PATCH 4/5] Documentation: add node files to sysfs ABI

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 24.04.2008 [09:13:52 +0200], Nick Piggin wrote:
> On Wed, Apr 23, 2008 at 11:32:52AM -0700, Nishanth Aravamudan wrote:
> > 
> > So, I think, we pretty much agree on how things should be:
> > 
> > Direct translation of the current sysctl:
> > 
> > /sys/kernel/hugepages/nr_hugepages
> >                       nr_overcommit_hugepages
> > 
> > Adding multiple pools:
> > 
> > /sys/kernel/hugepages/nr_hugepages -> nr_hugepages_${default_size}
> >                       nr_overcommit_hugepages -> nr_overcommit_hugepages_${default_size}
> >                       nr_hugepages_${default_size}
> >                       nr_overcommit_hugepages_${default_size}
> >                       nr_hugepages_${other_size1}
> >                       nr_overcommit_hugepages_${other_size2}
> > 
> > Adding per-node control:
> > 
> > /sys/kernel/hugepages/nr_hugepages -> nr_hugepages_${default_size}
> >                       nr_overcommit_hugepages -> nr_overcommit_hugepages_${default_size}
> >                       nr_hugepages_${default_size}
> >                       nr_overcommit_hugepages_${default_size}
> >                       nr_hugepages_${other_size1}
> >                       nr_overcommit_hugepages_${other_size2}
> >                       nodeX/nr_hugepages -> nr_hugepages_${default_size}
> >                             nr_overcommit_hugepages -> nr_overcommit_hugepages_${default_size}
> >                             nr_hugepages_${default_size}
> >                             nr_overcommit_hugepages_${default_size}
> >                             nr_hugepages_${other_size1}
> >                             nr_overcommit_hugepages_${other_size2}
> > 
> > How does that look? Does anyone have any problems with such an
> > arrangement?
> 
> Looks pretty good. I would personally lean toward subdirectories for
> hstates. Pros are that it would be a little easier to navigate from
> the shell, and maybe more regular to program for.

That's probably true -- and extracting the pagesize to which things
correspond should be simpler too. And perhaps that would allow for
easier output of meminfo for the various hugepage sizes?

> You could possibly have hugepages_default symlink as well to one of
> the directories of your choice. This could be used by apps which do
> not specify exactly what size they want...

Yep, that would seem sensible...or perhaps even have nr_hugepages in the
root directory (and other corresponding files directly symlink into the
default_size directory?).

> I don't know, just ideas.

Thanks for the feedback!

-Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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