From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79FC4C43331 for ; Fri, 27 Mar 2020 18:18:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 453C2208E4 for ; Fri, 27 Mar 2020 18:18:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585333114; bh=nD1ZASDin7IOUe/665O+N3wleArI2IiupnuXq6p37/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=yLn5tk02Sd1pAPfC6uF4NtEAJXArBm/uCnVQvKl1Yp+/q1l/fxi50BFSEeQ+uDmaH v8T52z5Eu3ymo1SeM+SkfkWY6EC1kqR08OZc7Gdn2nSZ59nKBeIdAbgLYaUBWi/vFi l2QCfYmSwP2SLCdYrU9dbWU79QM6dMGR4NFDS+VI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726758AbgC0SSd (ORCPT ); Fri, 27 Mar 2020 14:18:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:53184 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726738AbgC0SSd (ORCPT ); Fri, 27 Mar 2020 14:18:33 -0400 Received: from redsun51.ssa.fujisawa.hgst.com (unknown [199.255.47.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EFF742083E; Fri, 27 Mar 2020 18:18:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585333112; bh=nD1ZASDin7IOUe/665O+N3wleArI2IiupnuXq6p37/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=0MFRh6Tqf32c/CY26P6nrLMdJDOc6f/E8tygCg5stx2gYsuuEOpUS4B+rYa563rkI EeQfyM6ZB1JpwQkM72ZyTSn8teCyqqVAtimB3Ziln92WNuBiUGaqPVTo2g2o2vrJh4 P3ZF85J5gqJepjB2WMibEM8sfNyZI/gKEbAQ8QVI= Date: Sat, 28 Mar 2020 03:18:25 +0900 From: Keith Busch To: Tokunori Ikegami Cc: Chaitanya Kulkarni , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" Subject: Re: [PATCH] block, nvme: Increase max segments parameter setting value Message-ID: <20200327181825.GA8356@redsun51.ssa.fujisawa.hgst.com> References: <20200323182324.3243-1-ikegami.t@gmail.com> <20200324000237.GB15091@redsun51.ssa.fujisawa.hgst.com> <6b73db44-ca3f-4285-0c91-dc1b1a5ca9f1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sat, Mar 28, 2020 at 02:50:43AM +0900, Tokunori Ikegami wrote: > On 2020/03/25 1:51, Tokunori Ikegami wrote: > > On 2020/03/24 9:02, Keith Busch wrote: > > > We didn't have 32-bit max segments before, though. Why was 16-bits > > > enough in older kernels? Which kernel did this stop working? > > Now I am asking the detail information to the reporter so let me > > update later. That was able to use the same command script with the > > large data length in the past. > > I have just confirmed the detail so let me update below. > > The data length 20,531,712 (0x1394A00) is used on kernel 3.10.0 (CentOS > 64bit). > Also it is failed on kernel 10 4.10.0 (Ubuntu 32bit). > But just confirmed it as succeeded on both 4.15.0 (Ubuntu 32bit) and 4.15.1 > (Ubuntu 64bit). > So the original 20,531,712 length failure issue seems already resolved. > > I tested the data length 0x10000000 (268,435,456) and it is failed > But now confirmed it as failed on all the above kernel versions. > Also the patch fixes only this 0x10000000 length failure issue. This is actually even more confusing. We do not support 256MB transfers within a single command in the pci nvme driver anymore. The max is 4MB, so I don't see how increasing the max segments will help: you should be hitting the 'max_sectors' limit if you don't hit the segment limit first.