From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 1 Nov 2006 12:34:51 -0800 From: Andrew Morton Subject: Re: Page allocator: Single Zone optimizations Message-Id: <20061101123451.3fd6cfa4.akpm@osdl.org> In-Reply-To: <20061101182605.GC27386@skynet.ie> References: <20061027190452.6ff86cae.akpm@osdl.org> <20061027192429.42bb4be4.akpm@osdl.org> <20061027214324.4f80e992.akpm@osdl.org> <20061028180402.7c3e6ad8.akpm@osdl.org> <4544914F.3000502@yahoo.com.au> <20061101182605.GC27386@skynet.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: Nick Piggin , Christoph Lameter , KAMEZAWA Hiroyuki , linux-mm@kvack.org List-ID: On Wed, 1 Nov 2006 18:26:05 +0000 mel@skynet.ie (Mel Gorman) wrote: > I never really got this objection. With list-based anti-frag, the > zone-balancing logic remains the same. There are patches from Andy > Whitcroft that reclaims pages in contiguous blocks, but still with the same > zone-ordering. It doesn't affect load balancing between zones as such. I do believe that lumpy-reclaim (initiated by Andy, redone and prototyped by Peter, cruelly abandoned) is a perferable approach to solving the fragmentation approach. And with __GFP_EASYRECLAIM (please - I just renamed it ;)) (or using __GFP_HIGHMEM for the same thing) then some of the core lumpy-reclaim algorithm can be reused for hot-unplug. If you want to unplug a range of memory then it has to be in a zone which is 100% __GFP_EASY_RECLAIM (actually the name is still wrong. It should just be __GFP_RECLAIMABLE). The hot-unplug code will go through those pages and it will, with 100% reliability, rip those pages out of the kernel via various means. I think this can all be done. And hot-unplug isn't actually the interesting application. Modern Intel memory controllers apparently have (or will have) the ability to power down DIMMs. -- 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