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 823895226; Fri, 9 Feb 2024 04:03:57 +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=1707451437; cv=none; b=DEYPvDR/BacGdklwQfy6Cjqt1tijpNHSqO44ZkpfK+P0TeTRbWBrRA75V3WwAbiYySbYc4aEAHMqTU3x+KE7RFJ1H7r9/Kt9b7AzX/oCc0wy1/fcosrGI6yp3k2unRq4i5NloEpZp0yJhCySHweApWHn+n+WfeNNplEz3C5F0Mg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707451437; c=relaxed/simple; bh=i5fBQGLpAyvjOnEiViSE0N/eREgMuE439RWo72hOh/U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TeDjC2tMGhQyRz4EQY4ccYAw3u8hGbuskvGocVBGlT/SFUbZW4t7jeKIw5cc/pcijKFIq76yDYGhAKIvnZRpiR6io/LRpAkucAwqf4ERABvfIzMnucPh4w3nIv/CT9cetUr/dvajo66PF38J6I76cIafBHG97rkUGuh4hTVXyI4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DBp3Xw0i; 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="DBp3Xw0i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B256C433C7; Fri, 9 Feb 2024 04:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707451437; bh=i5fBQGLpAyvjOnEiViSE0N/eREgMuE439RWo72hOh/U=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=DBp3Xw0iCHb2JSSrUNbV/4vxKXLNvlnnQoEe7PbR8qSPI7l3TPk9/aF4Cj/E6+1En O7RvmHOTVuydzus+CcDVpADO8NNrnJIT2HAAICJnVEcs1qCYlYN7xqRxxZeXMcVyHC lGljYVBi2KVFv6+yEcPoasO+AVRdBFEYDJuQBz9biqJdpPg271iju2Vus0QYnAbHAx o81wMUXpwC5LjB26a7QcmszadzVPYS0R/6wrM4R44svYC7y3TCPZhPgAWo/G1DVtVw o29vXeHhba3ot+ld0q6Z19whaZwokglIybz36AC2eygni55yH08YjtTOAVggE6EcXi oFShv0xqQiOtg== Message-ID: <268af1af-f8e9-4e85-ad53-310392f7facd@kernel.org> Date: Fri, 9 Feb 2024 13:03:54 +0900 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 00/26] Zone write plugging Content-Language: en-US To: Bart Van Assche , linux-block@vger.kernel.org, Jens Axboe , linux-scsi@vger.kernel.org, "Martin K . Petersen" , dm-devel@lists.linux.dev, Mike Snitzer Cc: Christoph Hellwig References: <20240202073104.2418230-1-dlemoal@kernel.org> <548aa284-6c80-4f01-a5ce-bb16f64e9c85@kernel.org> <04fb99e4-3e67-4c69-b1ff-d8563dc3098d@acm.org> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <04fb99e4-3e67-4c69-b1ff-d8563dc3098d@acm.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/6/24 10:25, Bart Van Assche wrote: > On 2/5/24 16:07, Damien Le Moal wrote: >> On 2/6/24 03:18, Bart Van Assche wrote: >>> Are there numbers available about the performance differences (bandwidth >>> and latency) between plugging zoned write bios and zoned write plugging >>> requests? >> >> Finish reading the cover letter. It has lots of measurements with rc2, Jens >> block/for-next and ZWP... > Hmm ... as far as I know nobody ever implemented zoned write plugging > for requests in the block layer core so these numbers can't be in the > cover letter. No, I have not implemented zone write plugging for requests as I beleive it would lead to very similar results as zone write locking, that is, a potential problem with efficiently using a device in a mixed read/write workload as having too many plugged writes can lead to read starvation (blocking of read submission on request allocation when nr_requests is reached). > Has the bio plugging approach perhaps been chosen because it works > better for bio-based device mapper drivers? Not that it "works better" but rather that doing plugging at the BIO level allows re-using the exact same code for zone append emulation, and write ordering (if a DM driver wants the block layer to handle that). We had zone append emulation implemented for DM (for dm-crypt) using BIOs and in scsi sd driver using requests. ZWP unifies all this and will trivially allow enabling that emulation for other device types as well (e.g. NVMe ZNS drives that do not have native zone append support). -- Damien Le Moal Western Digital Research