From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 70CC4EC2; Wed, 16 Jul 2025 16:29:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752683379; cv=none; b=AZvUuOC97J91D807wNATALuz3byA8rADLwDnLqZXHxJE4oZ7cNXtFtz96aSBLraOXlMBfvKZK4jKXkS1/k0heDKgIe7n/r5IJ3j5aLebWg4ys7HwvKLjKLMN+dO061ixWrGw6h3mKLwkJxrgwuXAuMRwMuDwuAZWVKYvRZXbc2g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752683379; c=relaxed/simple; bh=7LtaZGbcu3N/ibo5xwvQDTM1d1oOAkSar/tn3F2rQEc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=N43Y4inLC4fz6W73tn7qyZ5m4iMLPDOJrZOhUc+d9lAhF4KvTvcxPF6/mZUW9Lmj9zgf5gjiOzMbBzBsTXnqODVzhavbNxwjShgOM/ML42C08is7qvlFSd80SXLa4202OQyGS6XWpS58CgOTbEm6W7xmsu3sAxUUyBzilcwQ36c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PMzghLaK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PMzghLaK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B964BC4CEE7; Wed, 16 Jul 2025 16:29:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752683376; bh=7LtaZGbcu3N/ibo5xwvQDTM1d1oOAkSar/tn3F2rQEc=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=PMzghLaK3//doW21Uo6om0hMmYJHZ/MkKaICDlyY7Jvfkq1OPbDagN8iKYP4K4tEA iL6Ju+zSsvFjyro+W5EB8KSs6JsDffUtExHr+3iQf3fpiEuYvStZWZMMt/jOsaBppY P5T+vSt1rIckK8vyCeUTw5Wkfpt/0/anAGdMyusBXpo44NswwzoXIztHjW34Ij4Y6+ BcPaGaRydunkb5ABqS/ItRUQgwNxHjYJzEp2xsGpzSu1+Mrl1rePKttcN3pj8cadrd n7F2YIj3OpWe1xKzVc6zZeO8RGlUSJTZowAkGVjCI4PCOheFQJMR0fOOdHY9v7+oB9 AKLSydxGzym3g== Message-ID: <284433c9-c11d-401f-8015-41faa9d0fde1@kernel.org> Date: Thu, 17 Jul 2025 00:29:27 +0800 Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: yukuai@kernel.org Subject: Re: [RFC PATCH] md: split bio by io_opt size in md_submit_bio() To: Coly Li , Christoph Hellwig Cc: Coly Li , linux-raid@vger.kernel.org, linux-block@vger.kernel.org, Yu Kuai , Xiao Ni , Hannes Reinecke , Martin Wilck , Keith Busch References: <20250715180241.29731-1-colyli@kernel.org> <20250716113737.GA31369@lst.de> <437E98DD-7D64-49BF-9F2C-04CB0A142A88@coly.li> <20250716114121.GA32207@lst.de> <20250716114533.GA32631@lst.de> <20250716121449.GB2043@lst.de> <20250716121745.GA2700@lst.de> <109C6212-FE63-4FD2-ACC3-F64C44C7D227@coly.li> Content-Language: en-US From: Yu Kuai In-Reply-To: <109C6212-FE63-4FD2-ACC3-F64C44C7D227@coly.li> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, 在 2025/7/16 20:23, Coly Li 写道: > >> 2025年7月16日 20:17，Christoph Hellwig 写道： >> >> On Wed, Jul 16, 2025 at 08:16:34PM +0800, Coly Li wrote: >>> >>>> 2025年7月16日 20:14，Christoph Hellwig 写道： >>>> >>>> On Wed, Jul 16, 2025 at 08:10:33PM +0800, Coly Li wrote: >>>>> Just like hanlding discard requests, handling raid5 read/write bios should >>>>> try to split the large bio into opt_io_size aligned both *offset* and >>>>> *length*. If I understand correctly, bio_split_to_limits() doesn't handle >>>>> offset alignment for read5 read/write bios. >>>> Well, if you want offset alignment, set chunk_sectors. >>>> >>> Do you mean setting max_hw_sectors as chunk_sectors? >> Setting both to the desired value (full stipe width). >> > Do you mean setting chunk_size as (chunk_size * data_disks)? This is deadlock… > > If opt_io_size is (chunk_size * data_disks), setting new max_hw_sectors as rounddown(current max_hw_sectors, opt_io_size) is good idea. I think round down max_hw_sectors to io_opt(chunk_size * data_disks) will really make things much easier, perhaps Christoph means this way. All you need to do is to handle not aligned bio and split that part, and for aligned bio fall back to use bio_split_to_limits(). Thanks, Kuai > > Thanks. > > Coly Li > >