Re: [PATCH 1/2] [REPOST] mm: show node to memory section relationship with symlinks in sysfs

Andrew Morton
2008-10-10T21:59:50Z

On Fri, 10 Oct 2008 14:33:57 -0700
Gary Hade <garyhade@us.ibm.com> wrote:

> On Fri, Oct 10, 2008 at 12:42:39PM -0700, Andrew Morton wrote:
> > On Thu, 9 Oct 2008 12:21:15 -0700
> > Gary Hade <garyhade@us.ibm.com> wrote:
> >
> > > Show node to memory section relationship with symlinks in sysfs
> > >
> > > Add /sys/devices/system/node/nodeX/memoryY symlinks for all
> > > the memory sections located on nodeX. For example:
> > > /sys/devices/system/node/node1/memory135 -> ../../memory/memory135
> > > indicates that memory section 135 resides on node1.
> >
> > I'm not seeing here a description of why the kernel needs this feature.
> > Why is it useful? How will it be used? What value does it have to
> > our users?
>
> Sorry, I should have included that. In our case, it is another
> small step towards eventual total node removal. We will need to
> know which memory sections to offline for whatever node is targeted
> for removal. However, I suspect that exposing the node to section
> information to user-level could be useful for other purposes.
> For example, I have been thinking that using memory hotremove
> functionality to modify the amount of available memory on specific
> nodes without having to physically add/remove DIMMs might be useful
> to those that test application or benchmark performance on a
> multi-node system in various memory configurations.
>

hm, OK, thanks. It does sound a bit thin, and if we merge this then
not only do we get a porkier kernel, we also get a new userspace
interface which we're then locked into.

So I'm inclined to skip this change until we have a stronger need?