From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 28 Oct 2006 16:47:26 +0900 From: KAMEZAWA Hiroyuki Subject: Re: Page allocator: Single Zone optimizations Message-Id: <20061028164726.04f89936.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20061027214324.4f80e992.akpm@osdl.org> References: <20061017102737.14524481.kamezawa.hiroyu@jp.fujitsu.com> <45347288.6040808@yahoo.com.au> <45360CD7.6060202@yahoo.com.au> <20061018123840.a67e6a44.akpm@osdl.org> <20061026150938.bdf9d812.akpm@osdl.org> <20061027190452.6ff86cae.akpm@osdl.org> <20061027192429.42bb4be4.akpm@osdl.org> <20061027214324.4f80e992.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: clameter@sgi.com, nickpiggin@yahoo.com.au, linux-mm@kvack.org List-ID: On Fri, 27 Oct 2006 21:43:24 -0700 Andrew Morton wrote: > On Fri, 27 Oct 2006 19:31:20 -0700 (PDT) > Christoph Lameter wrote: > > > So right now __GFP_HIGHMEM is an excellent hint telling the page allocator > > > that it is safe to satisfy this request from removeable memory. > > > > OK this works on i386 but most other platforms wont have a highmem > > zone. > > Under this proposal platforms which wish to implement physical hot-unplug > would need to effectively implement highmem. They won't keep to kmap the > pages to access their contents, but they will need to ensure that > unreclaimable allocations be constrained to the non-removable physical > memory. > > It's all pretty simple. But it'd be hacky to implement it in terms of > "highmem". It would be better if we could just tell the core MM "here's a > 4G zone" and "here's a 60G zone". The 60G zone is only used for > GFP_HIGHUSER allocations and is hence unpluggable. > > I don't think there's any other (practical) way of implementing hot-unplug. > Thank you for mentioning to memory-unplug. I was offlined. We (memory unplug collegues) tried dividing pgdat/zone/free_list for reclaimable memory. but all of them were rejected ;). IMHO, using zone was the simplest one. But hard-coded ZONE_EASYRECLAIM was not good looking.. I and Goto-san are still trying to improve sparsemem and *memory-hot-add*. So, memory-unplug stops but is not dead project. > But hot-unplug is just an example. My main point here is that it is > desirable that we get away from the up-to-four magical hard-wired zones in > core MM. > Hmm..zones should be dynamically defined at boot and configure how-to-zoning ? or just configurable at make ? Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org