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 7786BA92D for ; Thu, 29 Aug 2024 00:59:39 +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=1724893179; cv=none; b=Js25RSLCxzXVLAl9z3eTiUhYiSPDnPbdWvqnKwzXTs4xdHp1YHBdMV5WYRY9ZXiYIAbkp9bYfuHwdpE1Hl37dJrlstykL2HYCMi1ZPPRd7QBaRumzjI7htzisim6YGqGqcU0qzseItSPUCVLUwQ2Nf4ky0tIv9/Yj2PsVobppYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724893179; c=relaxed/simple; bh=lG1TS6xu37cZrPkHU229kCxGZsgY/h8wjKYKURamgN8=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=eWpfMU/wEcGIWHiNKRbGQz9GTS+ww4pMLpGgzmNvDtdFMJ0hc4Bme+zoo3wShr1aEt+qi7QhQfBeEbB+p/SsE8xUDPX3KvBto2hJLv+7uxqgVs9RFn5Fx8yXCwz45f4PxLAHE1kSYkpBv1zrWOcoGC6g77kOYG+7u5T4ahx8QKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KiO9nak8; 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="KiO9nak8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50B69C4CEC0; Thu, 29 Aug 2024 00:59:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724893178; bh=lG1TS6xu37cZrPkHU229kCxGZsgY/h8wjKYKURamgN8=; h=Date:Subject:To:References:From:In-Reply-To:From; b=KiO9nak8wMsA+xc/FkczgBdbDzxfoVDxbnK1EmCSFI/ZEWbWWyWE585yCdegggzva uVkbeNPK/rEG2Pt6zPbbGjVcbPgoyKDFtseZDAhULkvPPw+Pw1gaGONAYt37dXzJpH FJTfI7y+jusePkDRuZTAq93NlVp4khZ8ZbKvMo1ZcUNcgz5Dwjv0s37wqhtLExBZK1 gnHlXVCNC/j4NgeY5n0sNDOZqVLX3CPSovf2MvXv3vAXCVWNhJJixJQosWz0qBthqi bTH2LebdLGZ7MfrSbN3dRA5/X39+oJyzd2jOkTOFzvVPGtXwAC53boXt/9pg4ZsFDS Ihp4NspD06J3Q== Message-ID: <696d408a-b36d-4648-8eb4-93384cf2d65f@kernel.org> Date: Thu, 29 Aug 2024 09:59:37 +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 0/9] introduce the log_issue_time option To: Jens Axboe , Shin'ichiro Kawasaki , fio@vger.kernel.org, Vincent Fu References: <20240827070850.947037-1-shinichiro.kawasaki@wdc.com> From: Damien Le Moal Content-Language: en-US Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/29/24 02:06, Jens Axboe wrote: > On 8/27/24 1:08 AM, Shin'ichiro Kawasaki wrote: >> When write_lat_log option is set, fio outputs the 'clat' completion >> latency log file. This clat log can be used to analyze IO latency. This >> file can also be considered as an IO trace file as each IO entry can >> fully describe an IO when the --log_offset and --log_prio options are >> also used. However, using the clat log file as an IO trace is inaccurate >> because the time field of each entry uses millisecond units, which is >> too coarse for fast IOs (e.g. when using SSDs). This series proposes the >> new option 'log_issue_time' to address the inaccuracy problem. When this >> option is set, fio adds another field to the log file entries to log an >> IO issuing time in nanoseconds. >> >> The first four patches in the series clean up the current code as >> preparation. The 5th patch introduces the 'log_issue_time' option. The >> following two patches document the new option. The last two patches add >> two test cases to check the log file format. > > In general this looks fine, and I think it's a useful feature. However, > should we have an option to make the generic time in the log entry be > in nsec as well? I am not sure if it is that useful given that the entry time field does not directly correspond to any I/O time. But to be consistent with the other time fields, I may be good to add this option. That is easy to do. -- Damien Le Moal Western Digital Research