From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH v1 00/24] New fast registration API Date: Wed, 7 Oct 2015 09:30:22 -0700 Message-ID: <5615489E.2050307@sandisk.com> References: <560AE099.2080004@sandisk.com> <560AFB71.3010003@dev.mellanox.co.il> <560C30F4.50900@sandisk.com> <560C42CE.6090000@sandisk.com> <560CDDBC.8000400@dev.mellanox.co.il> <560D730C.9000302@sandisk.com> <560D9E69.70604@sandisk.com> <35618B90-4D6E-4036-A69B-4405F020D440@dev.mellanox.co.il> <560EA4A1.3080709@sandisk.com> <56138854.4040209@dev.mellanox.co.il> <20151007092024.GA18020@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20151007092024.GA18020-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig , Sagi Grimberg Cc: Sagi Grimberg , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "Nicholas A. Bellinger" List-Id: linux-rdma@vger.kernel.org On 10/07/2015 02:20 AM, Christoph Hellwig wrote: > On Tue, Oct 06, 2015 at 11:37:40AM +0300, Sagi Grimberg wrote: >> The issue is that the device requires the MR page array to have >> an alignment (0x40 for mlx4 and 0x400 for mlx5). When I modified the >> page array allocation to be non-coherent I didn't take care of >> alignment. > > Just curious: why did you switch away from the coheret dma allocations > anyway? Seems like the page lists are mapped as long as they are > allocated so the coherent allocator would seem like a nice fit. Hello Christoph, My concern is that caching and/or write combining might be disabled for DMA coherent memory regions. This is why I assume that calling dma_map_single() and dma_unmap_single() will be faster for registering multiple pages as a single memory region instead of using DMA coherent memory. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html