From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 14 Aug 2007 02:26:35 +0200 From: Andi Kleen Subject: Re: [PATCH 3/4] Embed zone_id information within the zonelist->zones pointer Message-ID: <20070814002635.GR3406@bingen.suse.de> References: <20070813225841.GG3406@bingen.suse.de> <20070813230801.GH3406@bingen.suse.de> <20070813234322.GJ3406@bingen.suse.de> <20070814000041.GL3406@bingen.suse.de> <20070814001659.GP3406@bingen.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andi Kleen , Mel Gorman , Lee.Schermerhorn@hp.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Mon, Aug 13, 2007 at 04:27:42PM -0700, Christoph Lameter wrote: > On Tue, 14 Aug 2007, Andi Kleen wrote: > > > > Ok then lets do it. > > > > Conversion only makes sense once an API with a explicit mask > > is in. Otherwise we have muddled semantics again. > > pci_set_consistent_dma_mask > > has that. While on x86 it is roughly identical (although the low level allocator is currently not very reliable) it makes a significant difference on some platforms. e.g. I was told on PA-RISC consistent memory is much more costly than non consistent ones. That's probably true on anything that's not full IO cache consistent. So while it would be reasonable semantics for x86 and IA64 it's not for everybody else. -Andi > -- 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