Re: about page migration on UMA

Christoph Lameter
2007-11-09T19:58:20Z

On Fri, 9 Nov 2007, Jared Hulbert wrote:

> On 11/9/07, Christoph Lameter <clameter@sgi.com> wrote:
> > On Fri, 9 Nov 2007, Jared Hulbert wrote:
> >
> > > For extreme low power systems it would be possible to shut down banks
> > > in SDRAM chips that were not full thereby saving power. That would
> > > require some defraging and migration to empty them prior to powering
> > > down those banks.
> >
> > Yes we have discussed ideas like that a couple of time. If you do have the
> > time then please make this work. You have my full support.
>
> So I would like to make this migration controlled by userspace. Are
> there mechanisms to allow that today? If you give me a starting point
> I'll look into something like this.

Well one idea is to generate a sysfs file that can take a physical memory
range? echo the range to the sysfs file. The kernel can then try to
vacate the memory range.

I am ccing the memory hotplug developers. They may be able to help you
better.