From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0910.google.com with SMTP id f1so521409rvb.26 for ; Fri, 07 Mar 2008 22:35:35 -0800 (PST) Message-ID: <86802c440803072235r3ca6013cufae3ed62cd67e60f@mail.gmail.com> Date: Fri, 7 Mar 2008 22:35:35 -0800 From: "Yinghai Lu" Subject: Re: [PATCH] [8/13] Enable the mask allocator for x86 In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200803071007.493903088@firstfloor.org> <20080307090718.A609E1B419C@basil.firstfloor.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andi Kleen , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, Mar 7, 2008 at 6:37 PM, Christoph Lameter wrote: > On Fri, 7 Mar 2008, Andi Kleen wrote: > > > - Disable old ZONE_DMA > > No fixed size ZONE_DMA now anymore. All existing users of __GFP_DMA rely > > on the compat call to the maskable allocator in alloc/free_pages > > - Call maskable allocator initialization functions at boot > > - Add TRAD_DMA_MASK for the compat functions > > - Remove dma_reserve call > > This looks okay for the disabling part. But note that there are various > uses of MAX_DMA_ADDRESS (sparsemem, bootmem allocator) that are currently > suboptimal because they set a boundary at 16MB for allocation of > potentially large operating system structures. That boundary continues to > exist despite the removal of ZONE_DMA? > > It would be better to remove ZONE_DMA32 instead and enlarge ZONE_DMA so > that it can take over the role of ZONE_DMA. Set the boundary for > MAX_DMA_ADDRESS to the boundary for ZONE_DMA32. Then the > allocations for sparse and bootmem will be allocated above 4GB which > leaves lots of the lower space available for 32 bit DMA capable devices. good. i like the idea... How about system with only 4G or less? YH -- 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