On Fri, Jun 10, 2011 at 09:55:29AM -0700, Paul E. McKenney wrote:

On Fri, Jun 10, 2011 at 04:59:54PM +0100, Matthew Garrett wrote:

quoted

For the server case, the low hanging fruit would seem to be 
finer-grained self-refresh. At best we seem to be able to do that on a 
per-CPU socket basis right now. The difference between active and 
self-refresh would seem to be much larger than the difference between 
self-refresh and powered down.

By "finer-grained self-refresh" you mean turning off refresh for banks
of memory that are not being used, right?  If so, this is supported by
the memory-regions support provided, at least assuming that the regions
can be aligned with the self-refresh boundaries.

I mean at the hardware level. As far as I know, the best we can do at 
the moment is to put an entire node into self refresh when the CPU hits 
package C6.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org