From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH for-3.11 7/7] IB/iser: Introduce fast memory registration model (FRWR) Date: Tue, 23 Jul 2013 16:47:15 +0200 Message-ID: <51EE9773.9050003@acm.org> References: <1374153931-7313-1-git-send-email-ogerlitz@mellanox.com> <1374153931-7313-8-git-send-email-ogerlitz@mellanox.com> <51ED1B8E.7070703@acm.org> <51ED2F97.2080400@mellanox.com> <51EE6FFE.8040802@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: Sagi Grimberg , roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, roid-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org, oren-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 07/23/13 16:21, Or Gerlitz wrote: > Bart, iSER's FMR and FRWR code works under the assumption that an SG > list is "4K aligned". For SGs which don't obey that assumption we're > using bounce buffer. > > Note that the SG "page" size used by FMRs/FRWRs doesn't have to be 1:1 > with the OS page size, so in that respect && down the road, we will > get rid of the bounce buffer thing with having another FMR/FRWR pool > whose "page" size is 512B and will be used for SG which are not "4K > aligned". Sorry but I had overlooked the bounce buffer patch. Regarding page sizes: is an InfiniBand HCA required to support a page size of 512 bytes ? To me it seems like the smallest page size supported by e.g. the ocrdma driver is 4KB. From ocrdma_query_device(): attr->page_size_cap = 0xffff000; Still regarding page sizes: shouldn't ib_alloc_fast_reg_page_list() and ib_alloc_fast_reg_mr() multiply the SG list length by PAGE_SIZE / SIZE_4K to compensate for page size differences on architectures where virtual memory pages are larger than 4KB ? Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html