From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 05/24] ibtrs: client: main functionality Date: Mon, 5 Feb 2018 16:14:43 +0200 Message-ID: References: <20180202140904.2017-1-roman.penyaev@profitbricks.com> <20180202140904.2017-6-roman.penyaev@profitbricks.com> <1517590473.2675.21.camel@wdc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roman Penyaev , Bart Van Assche Cc: "linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "danil.kipnis-EIkl63zCoXaH+58JC4qpiA@public.gmane.org" , "hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org" , "ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org" , "jinpu.wang-EIkl63zCoXaH+58JC4qpiA@public.gmane.org" , "axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org" List-Id: linux-rdma@vger.kernel.org > Indeed, seems sbitmap can be reused. > > But tags is a part of IBTRS, and is not related to block device at all. One > IBTRS connection (session) handles many block devices we use host shared tag sets for the case of multiple block devices. > (or any IO producers). Lets wait until we actually have this theoretical non-block IO producers.. > With a tag you get a free slot of a buffer where you can read/write, so once > you've allocated a tag you won't sleep on IO path inside a library. Same for block tags (given that you don't set the request queue otherwise) > Also tag > helps a lot on IO fail-over to another connection (multipath implementation, > which is also a part of the transport library, not a block device), where you > simply reuse the same buffer slot (with a tag in your hands) forwarding IO to > another RDMA connection. What is the benefit of this detached architecture? IMO, one reason why you ended up not reusing a lot of the infrastructure is yielded from the attempt to support a theoretical different consumer that is not ibnbd. Did you actually had plans for any other consumers? Personally, I think you will be much better off with a unified approach for your block device implementation. -- 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