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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 40222C2D0F2 for ; Tue, 31 Mar 2020 15:24:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16E2220786 for ; Tue, 31 Mar 2020 15:24:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="obQKA52V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730784AbgCaPY6 (ORCPT ); Tue, 31 Mar 2020 11:24:58 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:42990 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730521AbgCaPY5 (ORCPT ); Tue, 31 Mar 2020 11:24:57 -0400 Received: by mail-pf1-f193.google.com with SMTP id 22so10465262pfa.9 for ; Tue, 31 Mar 2020 08:24:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=6FahT8x90WNHEEj3oMiZ/ShKhSZD8ajLBlpxau/7+rU=; b=obQKA52V+aibNLR7ijxuIcGBoA6P2Jr4R6YdarkbEj60cnP08xZnf8tFcb7prYuVQK vSaZgdHxMbxpWCCB8X+9gljqaKIWv8mK3rC37kxEi3hMS+fol5ysxO3s86DYH6G6Z6Ia dwWLEOiwLuCNkpxJd3cbRHnlRrZno9LBSqVSUo8q8lO8IG6lkI0Zc07nP0E4AraUE7l0 pzsssu9ZuqhsFBdv0Qpeivm7yO0cSI1YM49nD6aHDrCyEzbVfEkv9bNX9FkiR4vB5oQM FrdBCGVQQm2pqZJSo6UulPImEcGvX52rbTFLkU8aDmkQ9Rse5ocb3lMrAOa3UNnPIONY Bzjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=6FahT8x90WNHEEj3oMiZ/ShKhSZD8ajLBlpxau/7+rU=; b=KkDLZer0KULF2xWHfGdY1D3/0FEuOnxFAF+MDOnW8B/MfCk8HmBVTy/OB6NTvM3vQK 6VOb2Z9V3yHok0Yh/UR5AGy/0YXowe97n7K8DSJyh5BLadixFALzVxiQ/2v9uQlLujA1 FaVnyvGhlPwuZIasanELA4uAxZeQb1FujPk58SbX0FlzcB0K2qwpM0llsPMKaiWRZdsu NSEGHvDH62gMOyVoN3uWF1b8J4EqVAaJDiaRkYEQryeLyab+zh/NXZ5RRcRmNpNPEjfL oah2etEErwu55uoWm2EtoJQ5rqURZXWkxTu8q73Era4ektQaw0t6BrZc8rjEYMzekRfh VdJw== X-Gm-Message-State: AGi0PuZolGe6COs0Let6fHUk8wALmnIbY9STpfjIcwxUvoB94qG33oYa 5h4W5Rb0p6C28rm8UfT6HTkrK6ix X-Google-Smtp-Source: APiQypKejXVVSk70bM7Kz1AwJxT32HiTMDJNu9AaEukwpa+Inc8Lv9B5MNiRM6mgILrcauM5QKaRpA== X-Received: by 2002:aa7:8a99:: with SMTP id a25mr5110325pfc.76.1585668294930; Tue, 31 Mar 2020 08:24:54 -0700 (PDT) Received: from ?IPv6:240b:10:2720:5510:a182:288:3ffa:432a? ([240b:10:2720:5510:a182:288:3ffa:432a]) by smtp.gmail.com with ESMTPSA id y4sm583215pfo.39.2020.03.31.08.24.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 31 Mar 2020 08:24:54 -0700 (PDT) Subject: Re: [PATCH] block, nvme: Increase max segments parameter setting value To: Keith Busch Cc: Ming Lei , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" , Chaitanya Kulkarni References: <20200324000237.GB15091@redsun51.ssa.fujisawa.hgst.com> <6b73db44-ca3f-4285-0c91-dc1b1a5ca9f1@gmail.com> <20200327181825.GA8356@redsun51.ssa.fujisawa.hgst.com> <20200330135323.GA32604@C02WT3WMHTD6> From: Tokunori Ikegami Message-ID: <6c35a4f9-af19-feff-6be0-d9c023d6c6b7@gmail.com> Date: Wed, 1 Apr 2020 00:24:50 +0900 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200330135323.GA32604@C02WT3WMHTD6> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi, On 2020/03/30 22:53, Keith Busch wrote: > On Mon, Mar 30, 2020 at 06:15:41PM +0900, Tokunori Ikegami wrote: >> But there is a case that the command data length is limited by 512KB. >> I am not sure about this condition so needed more investigation. > Your memory is too fragmented. You need more physically contiguous > memory or you'll hit the segment limit before you hit the length > limit. Try allocating huge pages. Thank you so much for your advise. I have confirmed that the 512KB case is limited by the 127 segments check below in ll_new_hw_segment().     if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(req->q)) { Also confirmed that the 4MB limit works correctly with the memory condition not fragmented too much. I will do abandon the patch to increase max segments as limited 4MB now by NVMe PCIe driver. Regards, Ikegami