Re: [patch 05/21] hugetlb: new sysfs interface

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

On 11.06.2008 [19:11:49 -0600], Nishanth Aravamudan wrote:
> On 10.06.2008 [05:02:34 +0200], Nick Piggin wrote:
> > On Sun, Jun 08, 2008 at 11:59:41AM -0700, Andrew Morton wrote:
> > > On Wed, 04 Jun 2008 21:29:44 +1000 npiggin@suse.de wrote:
> > > 
> > > > Provide new hugepages user APIs that are more suited to multiple hstates in
> > > > sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that
> > > > directory there will be a directory per-supported hugepage size, e.g.:
> > > > 
> > > > /sys/kernel/hugepages/hugepages-64kB
> > > > /sys/kernel/hugepages/hugepages-16384kB
> > > > /sys/kernel/hugepages/hugepages-16777216kB
> > > 
> > > Maybe /sys/mm or /sys/vm would be a more appropriate place.
> > 
> > I'm thinking all the random kernel subsystems under /sys/ should
> > rather be moved to /sys/kernel/. Imagine how much crap will be
> > under the root directory if every kernel subsystem goes there.

What random subsystems do you see under /sys that are better off under
/sys/kernel? Keep in mind, sysfs is an ABI, so moving things is tricky
if it's been in a mainline release.

> > The system is the kernel, afterall, the subsystems should be under
> > there (arguably /sys/kernel/mm/hugepages/ would be better again, in
> > fact yes Nish can we do that?).
> 
> It should be pretty easy. Just need to allocate and add an appropriate
> kobject like kernel_kobj somewhere in the main vm initialization path
> and then change the parent in my patch to be that one rather than
> kernel_kobj.

So I'm ready to start doing this, but am curious if you think you'll
want to move the other mm-related bits under /sys/kernel/mm too (e.g.,
/sys/kernel/slab)? If so, then we'll need to plan for it, as it's an ABI
change. If not, then we might have mm stuff in different locations.

Thanks,
Nish

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

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