On (02/03/07 15:15), Paul Mundt didst pronounce: > On Fri, Mar 02, 2007 at 02:50:29PM +0900, KAMEZAWA Hiroyuki wrote: > > On Thu, 1 Mar 2007 21:11:58 -0800 (PST) > > Linus Torvalds <[EMAIL PROTECTED]> wrote: > > > > > The whole DRAM power story is a bedtime story for gullible children. > > > Don't > > > fall for it. It's not realistic. The hardware support for it DOES NOT > > > EXIST today, and probably won't for several years. And the real fix is > > > elsewhere anyway (ie people will have to do a FBDIMM-2 interface, which > > > is against the whole point of FBDIMM in the first place, but that's what > > > you get when you ignore power in the first version!). > > > > > > > Note: > > I heard embeded people often designs their own memory-power-off control on > > embeded Linux. (but it never seems to be posted to the list.) But I don't > > know > > they are interested in generic memory hotremove or not. > > > Yes, this is not that uncommon of a thing. People tend to do this in a > couple of different ways, in some cases the system is too loaded to ever > make doing such a thing at run-time worthwhile, and in those cases these > sorts of things tend to be munged in with the suspend code. Unfortunately > it tends to be quite difficult in practice to keep pages in one place, > so people rely on lame chip-select hacks and limiting the amount of > memory that the kernel treats as RAM instead so it never ends up being an > issue. Having some sort of a balance would certainly be nice, though.
If the range of memory you want to offline is MAX_ORDER_NR_PAGES, anti-fragmentation should group pages you can reclaim into those size of chunks. It might simplify the number of hacks you have to perform to limit where the kernel uses memory. -- -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
