Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management

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

On Fri, Jun 10, 2011 at 08:11:21AM -0700, Paul E. McKenney wrote:

quoted

Of course, on a server, you could get similar results by having a very
large amount of memory (say 256GB) and a workload that needed all the
memory only occasionally for short periods, but could get by with much
less (say 8GB) the rest of the time.  I have no idea whether or not
anyone actually has such a system.

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.

Or am I missing your point?

							Thanx, Paul