From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH -mm 0/11] fix iommu sg merging problem Date: Wed, 24 Oct 2007 07:40:50 -0400 Message-ID: <471F2F42.1080806@garzik.org> References: <67bb10d9f4e9473ddc84d9839114602c1966f19f.tomof@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:46754 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753598AbXJXLk5 (ORCPT ); Wed, 24 Oct 2007 07:40:57 -0400 In-Reply-To: <67bb10d9f4e9473ddc84d9839114602c1966f19f.tomof@acm.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: FUJITA Tomonori Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, James.Bottomley@SteelEye.com, jens.axboe@oracle.com, greg@kroah.com, muli@il.ibm.com, paulus@samba.org, tony.luck@intel.com, davem@davemloft.net, kyle@parisc-linux.org, aacraid@adaptec.com, fujita.tomonori@lab.ntt.co.jp FUJITA Tomonori wrote: > IOMMUs merges scatter/gather segments without considering a low level > driver's restrictions. The problem is that IOMMUs can't access to the > limitations because they are in request_queue. > > This patchset introduces a new structure, device_dma_parameters, > including dma information. A pointer to device_dma_parameters is added > to struct device. The bus specific structures (like pci_dev) includes > device_dma_parameters. Low level drivers can use dma_set_max_seg_size > to tell IOMMUs about the restrictions. > > We can move more dma stuff in struct device (like dma_mask) to struct > device_dma_parameters later (needs some cleanups before that). > > This includes patches for all the IOMMUs that could merge sg (x86_64, > ppc, IA64, alpha, sparc64, and parisc) though only the ppc patch was > tested. The patches for other IOMMUs are only compile tested. > > Thanks to everyone for the comments on the previous submission > to linux-scsi. > > This is against 2.6.24-rc1. The same patchset is also available: > > git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git iommu-sg-fixes Are you interested in collecting patches to libata that eliminate the hand-rolled S/G splitting? e.g. now ata_fill_sg() and mv_fill_sg() can be made much more efficient. Again, thanks for doing this! It's been needed for a long time. Jeff