From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <464FCA28.9040009@cosmosbay.com> Date: Sun, 20 May 2007 06:10:16 +0200 From: Eric Dumazet MIME-Version: 1.0 Subject: Re: [rfc] increase struct page size?! References: <20070518040854.GA15654@wotan.suse.de> <20070519012530.GB15569@wotan.suse.de> <20070519181501.GC19966@holomorphy.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: William Lee Irwin III , Nick Piggin , Linux Kernel Mailing List , Linux Memory Management List , linux-arch@vger.kernel.org, Andi Kleen List-ID: Christoph Lameter a ecrit : > On Sat, 19 May 2007, William Lee Irwin III wrote: > >> However, there are numerous optimizations and features made possible >> with flag bits, which might as could be made cheap by padding struct >> page up to the next highest power of 2 bytes with space for flag bits. > > Well the last time I tried to get this by Andi we became a bit concerned > when we realized that the memory map would grow by 14% in size. Given > that 4k page size challenged platforms have a huge amount of page structs > that growth is significant. I think it would be fine to do it for IA64 > with 16k page size but not for x86_64. This reminds me Andi attempted in the past to convert 'flags' to a 32 bits field : http://marc.info/?l=linux-kernel&m=107903527523739&w=2 I wonder why this idea was not taken, saving 2MB per GB of memory is nice :) -- 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