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 82748C433F5 for ; Thu, 24 Feb 2022 02:07:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230027AbiBXCI0 (ORCPT ); Wed, 23 Feb 2022 21:08:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229976AbiBXCIY (ORCPT ); Wed, 23 Feb 2022 21:08:24 -0500 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0CAF2717C; Wed, 23 Feb 2022 18:07:53 -0800 (PST) Received: by mail-pf1-x434.google.com with SMTP id x18so582508pfh.5; Wed, 23 Feb 2022 18:07:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=Uv2rCp8QaBEfsJ8idQ0xOtWsAg2D33Aox4De34JFITE=; b=OtkOvAsDXiiIQwb0IXhNwjFB7mIU3sS9AVWAo4/DD8sy3AA+0favut4okIKw3WJ0BJ PUCLgD+3ZXT8J/qyxVdAa6G9CRxRnPtwePJ0847tAEZZ14Rccxk9KXnIyLdNNavtJA84 VvqQBKp7KwTj/kn3lzJ99zfV4oU7xWo3UbXpQ0ckRUAONzrQB1Wg997imPpXPWfBjiTz LnMtn922TEplmI58N0QibruJTemqrt0TGKDHjXk3ChS7Ml0eUdu6gQWxjyzwPIoFysMT RUiHFv9degsnc2bv9BZcQogR3ISza5XzslXJbI2nPericPZWLVy2AT7Xo+dD5E58EYzY W0jQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to; bh=Uv2rCp8QaBEfsJ8idQ0xOtWsAg2D33Aox4De34JFITE=; b=0qNuV5X7YW94n3Ip56pbFiRQspv6cUTe8IsaDZLX4cihzTwcKVlgcf7sgUuEli3u5D J2AiRvONYpkWEieMChJmjSx8Ke4G/mn/xN1UqDlUrEdBinJSsxjxDs7Eg4RjkZaasawi VSkwCHKDR+WkLqDYnaV22GcgL1GasWNIFXfGWbkxNPY33eZi2nZUWFle93h5GSgRycOu jpdIOa5E8yPqgF8fvqWSKamzsr31tJ/pfruOSherPJGMo+uMSBQ7FLQYhtGSdEYeGAG0 Q1/x+TsdpZrmpD0GrzgizPZAX8jfOxYt+8dWzId+LYVUn5jH4acoyi+vj4eUOTvNJcuS Tm8w== X-Gm-Message-State: AOAM533Kjkp9uHgq3xMdWD6GCJUa491a1DqyyBWTzm2S5f4tExwFcyKU YdTH/WMwVF+KDMhko9E1Ek1TiYHQS30= X-Google-Smtp-Source: ABdhPJwrZY3mxQAdKkSY1wspnRMI4eDzN1kUtRk5ug102s6I5QhQGcHfMNHYYYiNiucdcwqyT/FZZQ== X-Received: by 2002:a63:1719:0:b0:373:9a4a:368d with SMTP id x25-20020a631719000000b003739a4a368dmr561321pgl.134.1645668473172; Wed, 23 Feb 2022 18:07:53 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id m19sm800659pfk.215.2022.02.23.18.07.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Feb 2022 18:07:52 -0800 (PST) Sender: Tejun Heo Date: Wed, 23 Feb 2022 16:07:51 -1000 From: Tejun Heo To: Wang Jianchao Cc: Jens Axboe , Josef Bacik , Bart Van Assche , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC V4 1/6] blk: prepare to make blk-rq-qos pluggable and modular Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. And please don't add a custom interface to avoid modprobing. All it adds is unnecessary deviation. There's no benefit to echoing a selector to a custom sysfs file compared to explicitly modprobing it. Thanks. -- tejun