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 13:58:54 +0200 Message-ID: <51EE6FFE.8040802@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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51ED2F97.2080400-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sagi Grimberg Cc: Bart Van Assche , Or Gerlitz , 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 07/22/13 15:11, Sagi Grimberg wrote: > So just to clarify the flow: > . at connection establishment allocate pool of fastreg descriptors > . upon each IOP take a fastreg descriptor from the pool > . if it is not invalidated - invalidate it. > . register using FRWR. > . when cleanup_task is called - just return the fastreg descriptor to > the pool. > . at connection teardown free all resources. > Still to come: > . upon each IOP response, check if the target used remote invalidate - > if so mark relevant fastreg as valid. Hello Sagi and Or, Thanks for the clarifications. I have one more question though. My interpretation of section "10.6 Memory Management" in the IB specification is that memory registration maps a memory region that either has contiguous virtual addresses or contiguous physical addresses. However, there is no such requirement for an sg-list. As an example, for direct I/O to a block device with a sector size of 512 bytes it is only required that I/O occurs in multiples of 512 bytes and from memory aligned on 512-byte boundaries. So the use of direct I/O can result in an sg-list where the second and subsequent sg-list elements have a non-zero offset. Do you agree with this ? Are such sg-lists mapped correctly by the FRWR code ? 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