On Fri, Jun 10, 2011 at 10:52:48AM -0700, Paul E. McKenney wrote: > On Fri, Jun 10, 2011 at 06:23:07PM +0100, Matthew Garrett wrote: > > I haven't seen too many ARM servers with 256GB of RAM :) I'm mostly > > looking at this from an x86 perspective. > > But I have seen ARM embedded systems with CPU power consumption in > the milliwatt range, which greatly reduces the amount of RAM required > to get significant power savings from this approach. Three orders > of magnitude less CPU power consumption translates (roughly) to three > orders of magnitude less memory required -- and embedded devices with > more than 256MB of memory are quite common. I'm not saying that powering down memory isn't a win, just that in the server market we're not even getting unused memory into self refresh at the moment. If we can gain that hardware capability then sub-node zoning means that we can look at allocating (and migrating?) RAM in such a way as to get a lot of the win that we'd gain from actually cutting the power, without the added overhead of actually shrinking our working set. -- Matthew Garrett | mjg59@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>