Return-Path: Received: from mail-wi0-f173.google.com ([209.85.212.173]:33546 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755328AbbI2Gtb (ORCPT ); Tue, 29 Sep 2015 02:49:31 -0400 Received: by wiclk2 with SMTP id lk2so135735764wic.0 for ; Mon, 28 Sep 2015 23:49:30 -0700 (PDT) Subject: Re: [PATCH v1 01/24] IB/core: Introduce new fast registration API To: Sagi Grimberg , Christoph Hellwig , Bart Van Assche References: <1442482947-27785-1-git-send-email-sagig@mellanox.com> <1442482947-27785-2-git-send-email-sagig@mellanox.com> <5601C65F.8060403@sandisk.com> <5603A841.70509@dev.mellanox.co.il> <5609A9D0.8030607@sandisk.com> <20150929055907.GA29758@infradead.org> <560A341F.7030108@mellanox.com> Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org, "Nicholas A. Bellinger" From: Sagi Grimberg Message-ID: <560A3474.3040603@dev.mellanox.co.il> Date: Tue, 29 Sep 2015 09:49:24 +0300 MIME-Version: 1.0 In-Reply-To: <560A341F.7030108@mellanox.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 9/29/2015 9:47 AM, Sagi Grimberg wrote: >> Shouldn't higher layers take care of this? Trying to implement the same >> coalescing algorithm at various layers isn't very optimal, although we >> need to decide and document which one is responsible. > > The block layer can take care of it, but I'm not sure about NFS/RDS at > the moment (IIRC Steve specifically asked if this API would take care > of chunking contig sg elements) so I'd rather keep it in until we are > absolutely sure we don't need it. > > I can add a documentation statement for it. Actually its documented: * Constraints: * - The first sg element is allowed to have an offset. * - Each sg element must be aligned to page_size (or physically * contiguous to the previous element). In case an sg element has a * non contiguous offset, the mapping prefix will not include it. * - The last sg element is allowed to have length less than page_size.