From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 008.lax.mailroute.net (008.lax.mailroute.net [199.89.1.11]) (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 92C3A14198E; Thu, 13 Jun 2024 16:15:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718295322; cv=none; b=MdDR1pSYAN9o/XOFnMbqFvqWTDmigL9Sx0ZakH9OwaQa4Gq49SKvms74ng9USBcO7P2ltk9QOrZTDzJ3jrNAM6hmZ8n1N+ULug4uwkTEd19GF2FIwg/8GT3/VXYj2IIrg+0nf/X1xGVEGbpEYZsPz0vUJvR+qdLdQPYI79VhYP0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718295322; c=relaxed/simple; bh=whMfq11Dvw2ni6ZHzlG2G6+Nq2AQLkx4vq48AZNPPKA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CR67LLtwTMD4o30sXxSNVbM0dt1WeXWzlXjqHYcwOwai4i5Rh0tN+alkMx5kG/VC0SCPgQtH7uIlfMju1n8n0RNulVpMfT2ZvfuYngnqCBRVvbeG2ABl6CtGO/5wFXGfuHZ6DfGSDtfpnWAIFpXHkiXI/0uECfXE4BykY9YpB38= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=HrcpeDFR; arc=none smtp.client-ip=199.89.1.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="HrcpeDFR" Received: from localhost (localhost [127.0.0.1]) by 008.lax.mailroute.net (Postfix) with ESMTP id 4W0SDl5Rwcz6Cnk94; Thu, 13 Jun 2024 16:15:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1718295315; x=1720887316; bh=VkPfQbRg/V3TI9O9qndO+2G1 4jtGtT1qgCPkkoNwBOM=; b=HrcpeDFREjPrz+2v1PgNd01GJOe/dxhdUPjTA+LD pZHQgMHKcgmHMsTnqxvkBqa0/P4ZEFihu5ONnYpHZe+BSMFky0muLiknd/afYuDV BcxA0aSpy3tT8XMmzx2sIm8bLIKNQjkjl3VewPrxaHmYHtRr2MmroDea7T7ka0B5 wfGwUwQalf/nMiwXZiNfdhukh96/Cuus1SkqrbvaimWrx5zVLAEmdnWCQuJmRtV0 Kvvqf44yFMOywckrNLjaOaERTlaVKXHRF5G8F3A3WDNXXLJdHi1m9uAI3H95g41Z 3zQpI91h0FDjUCKPOhJmxB+LX+SoM1R5F09XCJZdeW9Yuw== X-Virus-Scanned: by MailRoute Received: from 008.lax.mailroute.net ([127.0.0.1]) by localhost (008.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id 0z4NuhIURIQq; Thu, 13 Jun 2024 16:15:15 +0000 (UTC) Received: from [IPV6:2620:0:1000:5e10:c543:208b:8ce4:f55a] (unknown [104.132.0.90]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 008.lax.mailroute.net (Postfix) with ESMTPSA id 4W0SDd3gd8z6Cnk9B; Thu, 13 Jun 2024 16:15:13 +0000 (UTC) Message-ID: <97a2b888-4dac-451c-bb9c-40d8dc52cd60@acm.org> Date: Thu, 13 Jun 2024 09:15:11 -0700 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC -next 0/7] blk-iocost: support to build iocost as kernel module To: Greg KH , Yu Kuai Cc: axboe@kernel.dk, tj@kernel.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 References: <20240613014937.1326020-1-yukuai1@huaweicloud.com> <2024061342-walk-cavalier-7e48@gregkh> Content-Language: en-US From: Bart Van Assche In-Reply-To: <2024061342-walk-cavalier-7e48@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/12/24 10:54 PM, Greg KH wrote: > On Thu, Jun 13, 2024 at 09:49:30AM +0800, Yu Kuai wrote: >> From: Yu Kuai >> >> Yu Kuai (7): >> kernfs: export pr_cont_kernfs_path() >> cgroup: export cgroup_parse_float >> block: export some API >> blk-iocost: factor out helpers to handle params from ioc_qos_write() >> blk-iocost: parse params before initializing iocost >> blk-iocost: support to free iocost >> blk-iocost: support to build iocost as kernel module > > No where do you say _why_ building this as a module is a good idea. > > Why do this at all? With CONFIG_BLK_CGROUP_IOCOST=y (as in the Android kernel), the blk-iocost kernel module causes a (small) runtime overhead, even if it is not being used. Thanks, Bart.