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=-10.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 8D193C433E0 for ; Tue, 2 Feb 2021 14:37:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C37E64EAC for ; Tue, 2 Feb 2021 14:37:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234405AbhBBOhY (ORCPT ); Tue, 2 Feb 2021 09:37:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234491AbhBBOcI (ORCPT ); Tue, 2 Feb 2021 09:32:08 -0500 Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A069C061786 for ; Tue, 2 Feb 2021 06:20:16 -0800 (PST) Received: by mail-il1-x136.google.com with SMTP id m20so11661322ilj.13 for ; Tue, 02 Feb 2021 06:20:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=t1KFZQVY/DxQ9liNlk4p5rHsTe1eztkSWG9pZLclAaM=; b=Roe+D204Ctd0npf37Ni88h2NOvgV6xaroR+sXYPETApFsoi3natQ82RzJtyfetiH1B xKjRZ9xOv73sQOXuTZIv0Cvxk4TvlcmI3HLnxu7j7lEY8zm/CUp7TRiuf5RPwHf0pSFo AC0/fAjcViva9q1JJjys0qAYFvLxqXHvetYiqtHFq/DMtv1fDDN7IGm3CyT3D5lAsTGJ C9zheHWkl4bUZbZ77ZDeeQCNE6BWSabVLKcpe9VLHxhYolYY7rL6r2i3kqldDzkMVWq1 zL43j+s4WZZnqIhUKrcXj5ds6pK3Ok6peFO8tTpUI8f8brdDU+yy2OvOvHhd9+Yby0NR YRKQ== 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-language :content-transfer-encoding; bh=t1KFZQVY/DxQ9liNlk4p5rHsTe1eztkSWG9pZLclAaM=; b=FyfBqTRA1LxpbBg9kZDF2tebd19tNig0FM4G7XZLO4GhnOIoHEyks77x1uhHyB6lRS 4uHYSSuPmZ638cCDf50o8LnOxAwmFQYmrFhssVfc9JTbzCbTgA7GnzYRFZ7Z/EhnBp85 4fvRp6Bn1BcLwlRafQ+ToEn5UHm0hmpGNJAk6V1MrvAb+TkiAhIrsC5JWvMOX08c1Rx4 6NgtFVwM/fYnjwlUHKZZq4vW66jMBMlUiqx7Ri6efi+50P3jD1xbEYeG5cZ4AILTSASv WH2IdTlKlPVUW4lWlS/iVEsUJQwV9jaDVmmjsuHCmY/3wrEI3Auf/+mY3V/Dlm7PjECC t/kA== X-Gm-Message-State: AOAM531LU0Qy5d5TJZonMncOjPTiuK5XmKy1cKTDb/le/9fMgLxBgbi8 SuxobRZSO37DoJoH/U6xYkeriKEmWJnJNVXy X-Google-Smtp-Source: ABdhPJxkdEchUAvYW/rkyrEcHpNi1VxOF9nH09cLjhcdz49G3SRvbrpf5/5CT4BvCNo00Q78q87qZQ== X-Received: by 2002:a05:6e02:b2c:: with SMTP id e12mr17301468ilu.143.1612275615609; Tue, 02 Feb 2021 06:20:15 -0800 (PST) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id p19sm11005722ilj.37.2021.02.02.06.20.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Feb 2021 06:20:14 -0800 (PST) Subject: Re: [PATCH] Revert "bfq: Fix computation of shallow depth" To: Jan Kara , Lin Feng Cc: paolo.valente@linaro.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org References: <20210129111808.45796-1-linf@wangsu.com> <20210202122836.GC17147@quack2.suse.cz> From: Jens Axboe Message-ID: Date: Tue, 2 Feb 2021 07:20:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210202122836.GC17147@quack2.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2/2/21 5:28 AM, Jan Kara wrote: > Hello! > > On Fri 29-01-21 19:18:08, Lin Feng wrote: >> This reverts commit 6d4d273588378c65915acaf7b2ee74e9dd9c130a. >> >> bfq.limit_depth passes word_depths[] as shallow_depth down to sbitmap core >> sbitmap_get_shallow, which uses just the number to limit the scan depth of >> each bitmap word, formula: >> scan_percentage_for_each_word = shallow_depth / (1 << sbimap->shift) * 100% > > Looking at sbitmap_get_shallow() again more carefully, I agree that I > misunderstood how shallow_depth argument gets used and the original code > was correct and I broke it. Thanks for spotting this! > > What I didn't notice is that shallow_depth indeed gets used for each bitmap > word separately and not for bitmap as a whole. I'd say this could use some > more documentation but that's unrelated to your revert. So feel free to add: > > Reviewed-by: Jan Kara I don't have the original patch (neither directly nor in the archive), so I had to hand-apply it. In any case, applied for 5.11, thanks. -- Jens Axboe