Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932176AbWIVTRV (ORCPT ); Fri, 22 Sep 2006 15:17:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932177AbWIVTRV (ORCPT ); Fri, 22 Sep 2006 15:17:21 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:15569 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S932176AbWIVTRU (ORCPT ); Fri, 22 Sep 2006 15:17:20 -0400 Date: Fri, 22 Sep 2006 12:17:06 -0700 (PDT) From: Christoph Lameter To: Andi Kleen cc: Martin Bligh , akpm@google.com, linux-kernel@vger.kernel.org, Christoph Hellwig , James Bottomley , linux-mm@kvack.org Subject: Re: [RFC] Initial alpha-0 for new page allocator API In-Reply-To: <200609222110.25118.ak@suse.de> Message-ID: References: <200609220817.59801.ak@suse.de> <200609222110.25118.ak@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1583 Lines: 39 On Fri, 22 Sep 2006, Andi Kleen wrote: > We already have that scheme. Any existing driver should be already converted > away from GFP_DMA towards dma_*/pci_*. dma_* knows all the magic > how to get memory for the various ranges. No need to mess up the > main allocator. That is not the case. The "magic" ends in arch specific *_alloc_dma_coherent function tinkering around with __GFP_DMA and in x86_64 in addition GFP_DMA32. > > Anyways, i suppose what could be added as a fallback would be a > really_slow_brute_force_try_to_get_something_in_this_range() allocator > that basically goes through the buddy lists freeing in >O(1) > and does some directed reclaim, but that would likely be a separate > path anyways and not need your new structure to impact the O(1) > allocator. Right. > I am still unconvinced of the real need. The only gaping hole was > GFP_DMA32, which we fixed already. And then about DMA zones being associated with arch independent memory ranges which is not the case. GFP_DMA32 just happens to be defined by a single arch and thus is has only one interpretation. > Ok there is aacraid with its weird 2GB limit, but in case there are > really enough users running into this broken then then the really_slow_* > thing above would be likely fine. And those cards are slowly going > away too. I agree. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/