From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C27918E1D; Tue, 18 Jun 2024 07:12:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718694768; cv=none; b=J+WnbHtBZw7pFlwJ781GX90sCddCktsfQg02xBKyDvPzxl5CgzIEfAeeVNOynGxBmEc2+meMArrqPT2Fat8MfrMXeEFDemzD+CuxnJVdPB9S3qbp/eTmmJ7V/7M9JFi+fdfpaTTHMW8bqGP065f9p5/H/4oTrt735WKmf366yiQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718694768; c=relaxed/simple; bh=84oEK2la+pdCXveM9q7mxMs8TSyM+0IrFfvfjlJkk+0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JNIB7Z6h1ITlZ6qUiG1mTKRK/cg/B/sOchYi4TRntpMpjKZc7XNHHWdnCGuX4/A69VS0GHcA4BIVMILLCAtA+f4xZicEM6FJAJjrxy6Wwqaz+YIQRTjsofFUrETimYiE2N3GS2NAN++4m/qCQG+gyoss7DrTDazo/omxS7U5InQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=3VPL7Qs5; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="3VPL7Qs5" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=SwIPm3HHHScXvzwW2YP/gyc4Q7ZKgoG76gRHm9Uog4I=; b=3VPL7Qs5nBb8dYE+xNNk3EILPn W9BVxnOriB/n/KMSny7rhUHQrV6I3/1PyIqyVcxSuMt2Q16ClbgX01J2QVda3Zz7V8VNKipvBUO1p uRh8lWRTB4C2Paea8e8S5HGG6jpT94k9z/NPBKt6EW/0sI+rCnSJSRbQLyx/dgv4HDE/G/wqeQbw0 pp1jO3kR084W244w+UOob9LruPvOfC7V/rZIRO4NfQEy2cosdkVClRPWxPtIHoUpmSR09x5Mztajq 4IRtKqIO7mIuwIjtQvTZz5GveM322Ci/GppSIoNZOs/oy/BOO9eS92wD1yy1YZwfHudMqlYuoBpZS ZCV1Tq0A==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sJT1D-0000000Dv6s-1VfH; Tue, 18 Jun 2024 07:12:39 +0000 Date: Tue, 18 Jun 2024 00:12:39 -0700 From: Christoph Hellwig To: Yu Kuai Cc: axboe@kernel.dk, tj@kernel.org, gregkh@linuxfoundation.org, bvanassche@acm.org, hch@infradead.org, josef@toxicpanda.com, lizefan.x@bytedance.com, hannes@cmpxchg.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, yukuai3@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: Re: [PATCH RFC v2 0/7] blk-iocost: support to build iocost as kernel module Message-ID: References: <20240618031751.3470464-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240618031751.3470464-1-yukuai1@huaweicloud.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Jun 18, 2024 at 11:17:44AM +0800, Yu Kuai wrote: > The motivation is that iocost is not used widely in our production, and > some customers don't want to increase kernel size to enable iocost that > they will never use, and it'll be painful to maintain a new downstream > kernel. Hence it'll be beneficially to build iocost as kernel module: > > - Kernel Size and Resource Usage, modules are loaded only when their > specific functionality is required. > > - Flexibility and Maintainability, allows for dynamic loading and unloading > of modules at runtime without the need to recompile and restart the kernel, > for example we can just replace blk-iocost.ko to fix iocost CVE in our > production environment. Given the amount of new exports and infrastructure it adds this still feels like a bad tradeoff.