From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: [RFC] libibverbs IB Device Memory support Date: Mon, 5 Jun 2017 11:44:00 -0500 (CDT) Message-ID: References: Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: ahmad omary Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ahmad Omary , Leon Romanovsky , Yishai Hadas , Tzahi Oved , Alex Rosenbaum , Ariel Levkovich , Liran Liss List-Id: linux-rdma@vger.kernel.org On Wed, 10 May 2017, ahmad omary wrote: > We have considered using mmap(), but As the size of device memory may be limited > ,the way to access it from host cpu may differ from vendor to vendor, due to > the 4K (page) aligment limitation of mmap() and the need not to directly > allow user to access the device memory, there is a need for a wrapper access > methods API that allows allocating and managing chunks that are smaller than > 4KB and not necessarily aligned to 4KB (page size). Why are 4k sized chunks a problem given that there are megabytes of memory in these devices? We are using various adapters already with an mmapped solution here. And I would prefer direct user space access to the memory. Fast access to the data stored in the NIC is important and it would be best not to have an intermediate layer that requires memcpy. -- 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