Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752243AbdHHQNU (ORCPT ); Tue, 8 Aug 2017 12:13:20 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:41659 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752059AbdHHQNS (ORCPT ); Tue, 8 Aug 2017 12:13:18 -0400 To: Suganath Prabu S Cc: JBottomley@Parallels.com, jejb@kernel.org, hch@infradead.org, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, Sathya.Prakash@broadcom.com, kashyap.desai@broadcom.com, linux-kernel@vger.kernel.org, chaitra.basappa@broadcom.com, sreekanth.reddy@broadcom.com, linux-nvme@lists.infradead.org Subject: Re: [PATCH v3 03/13] mpt3sas: SGL to PRP Translation for I/Os to NVMe devices From: "Martin K. Petersen" Organization: Oracle Corporation References: <1502183035-7441-1-git-send-email-suganath-prabu.subramani@broadcom.com> <1502183035-7441-4-git-send-email-suganath-prabu.subramani@broadcom.com> Date: Tue, 08 Aug 2017 12:12:13 -0400 In-Reply-To: <1502183035-7441-4-git-send-email-suganath-prabu.subramani@broadcom.com> (Suganath Prabu S.'s message of "Tue, 8 Aug 2017 14:33:45 +0530") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 925 Lines: 25 Suganath, > + /* > + ** Below code detects gaps/holes in IO data buffers. > + ** What does holes/gaps mean? > + ** Any SGE except first one in a SGL starts at non NVME page size > + ** aligned address OR Any SGE except last one in a SGL ends at > + ** non NVME page size boundary. > + ** > + ** Driver has already informed block layer by setting boundary rules > + ** for bio merging done at NVME page size boundary calling kernel API > + ** blk_queue_virt_boundary inside slave_config. > + ** Still there is possibility of IO coming with holes to driver because > + ** of IO merging done by IO scheduler. All this SGL to PRP code needs to go. If you are seeing anything that's not a valid PRP after setting the queue virt boundary then there's a block layer bug that needs to be debugged and fixed. Regardless of whether you are using an I/O scheduler or not. -- Martin K. Petersen Oracle Linux Engineering