From mboxrd@z Thu Jan 1 00:00:00 1970 From: paulmck@linux.vnet.ibm.com (Paul E. McKenney) Date: Fri, 10 Jun 2011 09:55:29 -0700 Subject: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management In-Reply-To: <20110610155954.GA25774@srcf.ucam.org> References: <1306499498-14263-1-git-send-email-ankita@in.ibm.com> <20110528005640.9076c0b1.akpm@linux-foundation.org> <20110609185259.GA29287@linux.vnet.ibm.com> <20110610151121.GA2230@linux.vnet.ibm.com> <20110610155954.GA25774@srcf.ucam.org> Message-ID: <20110610165529.GC2230@linux.vnet.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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: > > > 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