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 6495F3290B5 for ; Fri, 27 Feb 2026 04:59:41 +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=1772168381; cv=none; b=lpueLRdZGXcoDQc0tIcSOi1eRiuPNmKhSvHk7Dtncp8SLGJTw3fguYtxxBot2VRH6hmOQKZc+2nWisv5gyLyhtQPfInciesr496BAByhS/uOciZUtO+5nPWUqOigfIeUJ2v7Vrt9bEGa62ZSk+Vf5nVDo95hGlppQEbY1rQqNs4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772168381; c=relaxed/simple; bh=sLhKy7Esut2ue/s7EVLUrrGwalIr8kakZQTxDlpuPdA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=VFVE2Z8zjnC2/ajos4wJP85EIA7e76s5tjcY9LmWWclwpKB5lv2MAcwCx2JFFzbz7A2PHHDoQ4fNaE6tsBV52wmdmQbIRslSbLEOYNvOUedA72FTFtYmITB9J5zWhtkpbbYiJdrREsH2bHp5FmvvdIh6Zyc5biAA4LOoMJtlHFo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mK/hmVkJ; 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="mK/hmVkJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52B05C116C6; Fri, 27 Feb 2026 04:59:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772168381; bh=sLhKy7Esut2ue/s7EVLUrrGwalIr8kakZQTxDlpuPdA=; h=Date:Subject:To:References:From:In-Reply-To:From; b=mK/hmVkJpfwWrAJzCwrNK6T/FsMSNqFCoHB4ZaZg7Yn+kfc9IwwzTZ3CyuO3VsMgU LsR+HnbtJOyLGcHa5oC40ZQj4s/iz7zILdmUn9Gx2TKwoJgI/chv7RsYzrCq7sidKG MLOwzsn/TN+L6stZ/2hIQFiv1MGwpMsdVOXJnk3xNuDVEd+oz5LIcT6vUxAlvPDpjn LI81Fuo3vAGS9qj5An+yIej6nazjnhIqfYV8qlDQkzgbQTUcoasHTdbkV+llqKNlCo Ru8+ymrso/kdpKaxGNY2JLxr15m+LCAPqTPhCxQ7eP6aGgjNvipOrrycnOJ6l5+mNI LqsJR4mc646Dw== Message-ID: Date: Fri, 27 Feb 2026 13:59:39 +0900 Precedence: bulk X-Mailing-List: fio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/8] zbd: introduce write_zone_remainder option To: Shin'ichiro Kawasaki , fio@vger.kernel.org, Jens Axboe , Vincent Fu References: <20260216075936.3318729-1-shinichiro.kawasaki@wdc.com> <20260216075936.3318729-4-shinichiro.kawasaki@wdc.com> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20260216075936.3318729-4-shinichiro.kawasaki@wdc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/16/26 16:59, Shin'ichiro Kawasaki wrote: > When the specified block size is not aligned with the zone size or the > write pointer positions at workload start, write workloads create > unwritten remainder areas at the ends of zones. These remainder areas > leave zones in the open condition. This disrupts the intended write > target zone selection. > > Previous commits e1a1b59b0b9b ("zbd: finish zones with remainder smaller > than minimum write block size") and e2e29bf6f830 ("zbd: finish zone when > all random write target zones have small remainder") attempted to solve > this problem by issuing zone finish operation for zones with small > remainders. However, this approach caused performance degradation due to > two reasons. First, the zone finish operation requires substantial > execution time. Second, zone finish operation requires to wait for in- > flight writes from other jobs to complete, which is done by calling > io_u_quiesce() before the zone finish operation. > > To avoid the performance degradation, introduce the new option named > "write_zone_remainder". When the option is specified, issue writes to > the remainder areas instead of issuing zone finish operation. The write > operation makes the zones in the full condition in the same manner as > the zone finish operation, freeing up the zone resource of the device > and enabling writing to other zones. Also when the option is set, skip > the io_u_quiesce() which was required before the zone finish operation. > The performance benefit by eliminating the waits on in-flight writes are > particularly significant in asynchronous I/O workloads, where the write > operations to the remainder areas are managed as part of queued I/Os. > > The drawback of this approach is that writing these remainders requires > write sizes smaller than the minimum block size. As a result, when using > the write_zone_remainder option, the random map feature must be disabled > using the norandommap=1 option, which is automatically done when the > option is specified. Looks OK to me. Reviewed-by: Damien Le Moal -- Damien Le Moal Western Digital Research