From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (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 A125E255F28; Mon, 27 Apr 2026 01:30:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777253413; cv=none; b=NPJtxJWc0ddqvJ+OpcjCFaAJcyLsdWk8KhuWF1gPJ6XWeuQFP6m5CHuGMlTR7R9sE8Li62yCWWEr0a/x1BZ0ZR7Ytxl9T+Hxg7MlIq39Ta23t1Oo2KNBWzXh4/XPudwhJudzkRr/H7/a1zezIrelv8rQTXd4vdzlPUzsDeNEaCU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777253413; c=relaxed/simple; bh=acjbu6UIaVoWP0uAA66KF2HD4oHsAtt1U3RQzTygfgA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XHdR3iTdy0ujbKxIxq3ABHBfZ2W1wJgSpGHIeZ53n12hbcRoIsgrWhrhsgBvYDDSU+3EM6ieLkpPcIbKObN3fpnxzybLR/m4Gp58dL+ZDwGQKNqn2cjJbTbSNGHQ5dI4iiiuWraRJ1E/Tp8WTPPCYxvOfZ6/Id7sHjFQ5ACz1Pw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=PJID8kaK; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="PJID8kaK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Message-ID:Date:MIME-Version:Subject:To:From: Content-Type; bh=p3WgPpPfz2Bbmyji9QfrGWWEt38T46v9GT1N7YF6YB8=; b=PJID8kaKdsJ2JKKIZcv+EQPWVWkQm6/XMf/rMzAtuy6GW5BpgZNraAZ3/rttR+ mxDNvvlH8NJ6/pyuR7/l0YrkbQmF0qj+NGBV9Daj554zBjurIJYjNWmkUVMI/YC0 eB0Fk4Ez/Rl9Y1YUVOQ4ZtKOVm0BAmQuXRAocb1FGHTyg= Received: from [192.168.100.68] (unknown []) by gzga-smtp-mtada-g1-0 (Coremail) with SMTP id _____wCX8n__u+5pkitQBw--.52059S2; Mon, 27 Apr 2026 09:29:41 +0800 (CST) Message-ID: Date: Mon, 27 Apr 2026 09:29:32 +0800 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 v3 2/2] ext4: allow clearing mballoc stats through mb_stats To: Baokun Li , Theodore Tso Cc: adilger.kernel@dilger.ca, ojaswin@linux.ibm.com, ritesh.list@gmail.com, yi.zhang@huawei.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, wangguanyu@vivo.com, Baolin Liu , Andreas Dilger References: <20260422015026.7170-1-liubaolin12138@163.com> <20260422015026.7170-3-liubaolin12138@163.com> <20260423161947.GB68318@macsyma-wired.lan> <592456a9-ce45-4967-a7c4-4ed80e908bac@163.com> <5eaa521b-28b0-4c2a-a33d-57d1449f125e@linux.alibaba.com> From: liubaolin In-Reply-To: <5eaa521b-28b0-4c2a-a33d-57d1449f125e@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCX8n__u+5pkitQBw--.52059S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxXFy5JFWkuFyxCw4fXF15twb_yoW5Kw1Dpr 4Yqa42vF45XFyjvwn7KF4kJr1Utr9xJ3y7JrnxC3y29F4DtrySvF1SkrW5tF9Fkry8Zayr Zr4j9F9xAayjvFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UY0PhUUUUU= X-CM-SenderInfo: xolxutxrol0iasrtmqqrwthudrp/xtbC6QVGEWnuvAW4LAAA3R Dear Baokun, Thank you and Ted for your review and suggestions. I will incorporate your suggestions and submit the v4 patch as soon as possible. Thanks, Baolin 在 2026/4/24 17:34, Baokun Li 写道: > > On 2026/4/24 16:09, liubaolin wrote: >> >> >> 在 2026/4/24 0:19, Theodore Tso 写道: >>> On Wed, Apr 22, 2026 at 09:50:25AM +0800, Baolin Liu wrote: >>>> From: Baolin Liu >>>> >>>> Make /proc/fs/ext4//mb_stats writable and clear the runtime >>>> mballoc statistics when 0 is written. >>> >>> At the moment to enable mb_stats the system administrator needs to >>> write "1" to /sys/fs/ext4//mb_stats, and writing "0" to the sysfs >>> file will pauce the statistics colleciton (but not clear the >>> statistics).  Adding a way to clear the statistics by writing to the >>> procfs file might be confusing to users. >>> >>> So.... as a suggestion, if you're adding to the ability to write to >>> /proc/fs/.../mb_stats, what if we make things work by >>> >>>     * Write 1 to /proc/fs/.../mb_stats to  enable statistics collection >>>     * Write 0 to /proc/fs/.../mb_stats to  disable statistics collection >>>     * Write -1 to /proc/fs/.../mb_stats to clear statistics counters >>> >>> And then deprecate the /sys/fs/.../mb_stats variable (but we probably >>> won't be able to remove it for at least a year or two). >>> >>>                                         - Ted >> Dear Ted, Baokun, >>    Thank you for your review and suggestions. >>    Since you mentioned that /sys/fs/.../mb_stats cannot be deleted in >> the short term, >>    I plan to modify and submit a v4 patch according to the following >> strategy. >> >>    1. Change `/proc/fs/.../mb_stats` to read-write mode. >>     * Read `/proc/fs/.../mb_stats` to show statistics counters. >>     * Write 0 to `/proc/fs/.../mb_stats` to disable statistics >> collection. >>     * Write 1 to `/proc/fs/.../mb_stats` to enable statistics collection. >>     * Write 2 to `/proc/fs/.../mb_stats` to clear statistics counters. >> >>    2. Do not delete the `/sys/fs/.../mb_stats` node for now; implement >> the same write control logic. >>     * Write 0 to `/sys/fs/.../mb_stats` to disable statistics collection. >>     * Write 1 to `/sys/fs/.../mb_stats` to enable statistics collection. >>     * Write 2 to `/sys/fs/.../mb_stats` to clear statistics counters. >> >>     Delete `/sys/fs/.../mb_stats` later when it is possible to delete it. >> >>    3. Modify the relevant documentation for `mb_stats`. >>     Documentation/ABI/testing/sysfs-fs-ext4 >>     Documentation/admin-guide/ext4.rst >>     Documentation/filesystems/proc.rst >> >>    Compared to your suggestion, I recommend using the value 2 for the >> clear operation because s_mb_stats is an unsigned int variable, and >> using -1 requires changing the variable type. >>    I suggest avoiding changing the s_mb_stats variable type unless >> absolutely necessary. >> >>    Do you think this modification is appropriate? >>    If there are no problems, I will start modifying the code and >> submit the v4 patch as soon as possible. > > For the clear command, we only handle it without storing it, so s_mb_stats > remains unchanged and still stores only 0 and non-zero values to represent > disabled and enabled, respectively. Otherwise, you will have to deal with > a large number of s_mb_stats checks > > That means the /sys/fs/.../mb_stats interface does not need to support > clearing, but it might make sense to add a deprecation warning there. > > Then in `/proc/fs/.../mb_stats`, writing 0 or a positive number passes > it to s_mb_stats, writing -1 performs a reset, and other negative values > return -EINVAL. > > > Cheers, > Baokun >