Return-Path: Received: from mail-lb0-f193.google.com ([209.85.217.193]:33883 "EHLO mail-lb0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbcFUN4t (ORCPT ); Tue, 21 Jun 2016 09:56:49 -0400 Subject: Re: [PATCH v2 01/24] mlx4-ib: Use coherent memory for priv pages To: Yishai Hadas , Chuck Lever References: <20160616143518.GX5408@leon.nu> <576315C9.30002@gmail.com> <652EBA09-2978-414C-8606-38A96C63365A@oracle.com> <20160617092018.GZ5408@leon.nu> <4D23496A-FE01-4693-B125-82CD03B8F2D4@oracle.com> <20160618105650.GD5408@leon.nu> <5D0A6B47-CB71-42DA-AE76-164B6A660ECC@oracle.com> <57666E14.2070802@gmail.com> <20160620054453.GA1172@leon.nu> <12ee28bb-b838-ed4c-5f84-0cb8f1760d63@dev.mellanox.co.il> Cc: leon@kernel.org, Or Gerlitz , Yishai Hadas , linux-rdma , Linux NFS Mailing List , Majd Dibbiny From: Sagi Grimberg Message-ID: <5769479C.8070605@gmail.com> Date: Tue, 21 Jun 2016 16:56:44 +0300 MIME-Version: 1.0 In-Reply-To: <12ee28bb-b838-ed4c-5f84-0cb8f1760d63@dev.mellanox.co.il> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: > Just found the root cause of the problem, it was found to be a hardware > limitation that is described as part of the PRM. The driver code had to > be written accordingly, confirmed that internally with the relevant people. > > From PRM: > "The PBL should be physically contiguous, must reside in a > 64-byte-aligned address, and must not include the last 8 bytes of a page." > > The last sentence pointed that only one page can be used as the last 8 > bytes should not be included. That's why there is a hard limit in the > code for 511 entries. > > Re the candidate fix that you sent, from initial review it makes sense, > we'll formally confirm it soon after finalizing the regression testing > in our side. > > Thanks Chuck and Sagi for evaluating and working on a solution. Thanks Yishai, That clears up the root-cause. Does the same holds for mlx5? or we can leave it alone?