From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4506F2B9.5020600@google.com> Date: Tue, 12 Sep 2006 10:47:37 -0700 From: Martin Bligh MIME-Version: 1.0 Subject: Re: [PATCH 0/8] Optional ZONE_DMA V1 References: <20060911222729.4849.69497.sendpatchset@schroedinger.engr.sgi.com> <20060912133457.GC10689@sgi.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Jack Steiner , Linux Memory Management , Nick Piggin , Christoph Hellwig , linux-ia64@vger.kernel.org, Marcelo Tosatti , Arjan van de Ven , KAMEZAWA Hiroyuki , Andi Kleen List-ID: Resending. Your outbound email address is invalid (Christoph Lameter ), as is the address for linux-mm Christoph Lameter wrote: > On Tue, 12 Sep 2006, Jack Steiner wrote: > > >>I'm missing something here. On Altix, currently ALL of the memory is reported >>as being in the DMA zone: >> >> % cat /proc/budd* >> Node 0, zone DMA 3015 116 4 1 ... >> Node 1, zone DMA 4243 355 15 3 ... >> Node 2, zone DMA 4384 113 6 4 ... >> >> % cat /proc/zoneinfo >> Node 0, zone DMA >> pages free 5868 >> ... >> >>The DMA slabs are empty, though. > > > This is wrong. All memory should be in ZONE_NORMAL since we have no DMA > restrictions on Altix. PPC64 works the same way, I believe. All memory is DMA'able, therefore it all fits in ZONE_DMA. The real problem is that there's no consistent definition of what the zones actually mean. 1. Is it DMA'able (this is stupid, as it doesn't say 'for what device' 2. Is it permanently mapped into kernel address space. Given an inconsistent set of questions, it is unsuprising that we come up with an inconsistent set of answers. We're trying to answer a 2D question with a 1D answer. What is really needed is to pass a physical address limit from the caller, together with a flag that says whether the memory needs to be mapped into the permanent kernel address space or not. The allocator then finds the set of zones that will fulfill this criteria. But I suspect this level of change will cause too many people to squeak loudly. M. -- 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