From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH WIP 21/43] mlx5: Allocate a private page list in ib_alloc_mr Date: Wed, 22 Jul 2015 19:51:14 +0300 Message-ID: <55AFCA02.5050907@dev.mellanox.co.il> References: <1437548143-24893-1-git-send-email-sagig@mellanox.com> <1437548143-24893-22-git-send-email-sagig@mellanox.com> <20150722164605.GB6443@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150722164605.GB6443-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig , Sagi Grimberg Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Liran Liss , Oren Duer List-Id: linux-rdma@vger.kernel.org On 7/22/2015 7:46 PM, Christoph Hellwig wrote: > Just curious: what's the tradeoff between allocating the page list > in the core vs duplicating it in all the drivers? Does the driver > variant give us any benefits? It's not necessarily a page list... (i.e. a real scatterlist). I it will make more sense in patch 41/43. Moreover, as I wrote in the cover-letter. I noticed that several drivers keep shadows anyway for various reasons. For example mlx4 sets the page list with a preset-bit (related to ODP...) so at registration time we see the loop: for (i = 0; i < mr->npages; ++i) mr->mpl[i] = cpu_to_be64(mr->pl[i] | MLX4_MTT_FLAG_PRESENT); Given that this not a single example, I'd expect drivers to skip this duplication (hopefully). Sagi. -- 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