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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E7C5C433FE for ; Thu, 24 Feb 2022 02:50:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230168AbiBXCu6 (ORCPT ); Wed, 23 Feb 2022 21:50:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230113AbiBXCuz (ORCPT ); Wed, 23 Feb 2022 21:50:55 -0500 Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62945237437; Wed, 23 Feb 2022 18:50:26 -0800 (PST) Received: by mail-pj1-x1030.google.com with SMTP id v4so772073pjh.2; Wed, 23 Feb 2022 18:50:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=0pXW77xbSqoqd07SPOdMy6+frewnUErjG3BJoCU9xDQ=; b=BLl5H9NX6YUNRD93h7c/vngLNJjudh/21VVtQn4DmFm4iDSShGw+uLt07zvfShhW07 dBYZBERO7cmVboh9TwHp4FnA0CzWX/LLjG/N9A4qmDJc5UgIOmuW9HBCw4Jqf0OUHbsN ju92gxmIxzoNxkGEBgCoHLq0olkXCLU1qmV91MD/PB7gdQlmtmr8FSSTFasK5a17Dibc jiOodnBm1xqhGEo+nLPFpXvTQlQH7f2ma5h9pNIJdcUVegGGpIjCsFujiF88i4MZXsyJ CHvy3p+RAGAQvwJKOxFy+hPumyv6LsvMokjYvbhpB0iuqqvs9VOli87W8AT8tO1xriAE EXLA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=0pXW77xbSqoqd07SPOdMy6+frewnUErjG3BJoCU9xDQ=; b=A7gx/tmD8EZ+KsSnFgwjsbzZRrt3IMALyhPROB22cfqeS6r61OaKl7lm51pU80KYpY GAG4BXOCH4gSQjbtA/taZ0WPmHmQiXkwZdkHS8qp3CIo0mVJmmXklXDps/NIGWJEmfdk /bOC4jRN1bRE71Ii6xkcrKQV3pQWQplowyK+aZM6ji3hv1pWmM0WS6DEsYv9wmcQpzJR 4Sw35iwpZsiM9sIThaLox7Wf39m0JcLB+KJxtZV3q5BsMNKH7GTSDVMDKBlgk5PUHKEf hHuL0h4YxyeZEoQVgNiaTRxX2wISoylbfczlYOBRq7f/bCEK2VxilJY1aftDbx2hKJvC P7eA== X-Gm-Message-State: AOAM5334HNE+ouKYRUtGi0jue34lTE82T3qWFs6SRU0ZXwFRny3rYITi gnt8TtIyYq4wvTjeCqhP3s4= X-Google-Smtp-Source: ABdhPJz24dHKQmcXqS7azyJDfNBw3zXK87BYAbvO4kajEuZofKqEzzgChDHeA43qUG4bxXTECXNDiA== X-Received: by 2002:a17:90a:fb84:b0:1bc:4d16:51fb with SMTP id cp4-20020a17090afb8400b001bc4d1651fbmr12561044pjb.22.1645671025820; Wed, 23 Feb 2022 18:50:25 -0800 (PST) Received: from [172.20.119.15] ([61.16.102.69]) by smtp.gmail.com with ESMTPSA id 84sm906752pfx.181.2022.02.23.18.50.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Feb 2022 18:50:25 -0800 (PST) Message-ID: <7489a7f8-2589-29de-1c95-b99d1d9b1850@gmail.com> Date: Thu, 24 Feb 2022 10:50:22 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [RFC V4 1/6] blk: prepare to make blk-rq-qos pluggable and modular Content-Language: en-US To: Tejun Heo Cc: Jens Axboe , Josef Bacik , Bart Van Assche , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220217031349.98561-1-jianchao.wan9@gmail.com> <20220217031349.98561-2-jianchao.wan9@gmail.com> <2e17c058-8917-4a37-896e-1093446339f6@gmail.com> <39db454d-ca30-fb42-3d72-899efa34fb78@gmail.com> From: Wang Jianchao In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/2/24 10:07 上午, Tejun Heo wrote: > Hello, > > On Thu, Feb 24, 2022 at 09:51:04AM +0800, Wang Jianchao wrote: >> The initial version of this patchset has two targets： >> (1) Add a sysfs interface to open/close the policy per device. Then we needn't >> waste cpu cycles and memory if the device doesn't need the policy. >> (2) Make the policies modular, then it easy to maintain the code of policy in >> production environment as we only need to close the policy and replace the >> .ko file. >> >> The loading module when open policy in sysfs interface is just to avoid modprobe >> manually. There is similar operation when switch io scheduler. > > Each rq-qos mechanism already needs and has a way to turn off itself. > There's no reason to add another layer on top. If the current way of > disabling isn't efficient, we should improve that instead of adding a new > layer of interface on top. Yes, right now, every policy has their own way to turn off, but we always need to iterate the rqos list and enter into the policy's callback to check it. And every blkio cgroup needs to allocate memory for it even we don't use it. I don't this patchset is adding a new layer, but blk-rq-qos layer has been already there , we just add a unified interface to open/close the policies. Thanks Jianchao