linux-kernel - Re: [PATCH v2] f2fs: change write

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Date:   Tue, 3 Nov 2020 17:01:36 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <daejun7.park@...sung.com>,
        "jaegeuk@...nel.org" <jaegeuk@...nel.org>,
        "chao@...nel.org" <chao@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jieon Seol <jieon.seol@...sung.com>,
        Sang-yoon Oh <sangyoon.oh@...sung.com>,
        Mankyu PARK <manq.park@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        Keoseong Park <keosung.park@...sung.com>,
        SEUNGUK SHIN <seunguk.shin@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        Jaemyung Lee <jaemyung.lee@...sung.com>
Subject: Re: [PATCH v2] f2fs: change write_hint for hot/warm nodes

On 2020/11/3 16:38, Daejun Park wrote:
> In the fs-based mode of F2FS, the mapping of hot/warm node to
> WRITE_LIFE_NOT_SET should be changed to WRITE_LIFE_SHORT.
> 
> As a result of analyzing the write pattern of f2fs using real workload,
> hot/warm nodes have high update ratio close to hot data.[*]
> However, F2FS passes write hints for hot/warm nodes as WRITE_LIFE_NOT_SET.
> 
> Furthermore, WRITE_LIFE_NOT_SET is a default value of write hint when it is
> not provided from the file system.
> In storage, write_hint is used to distinguish streams (e.g. NVMe).
> So, the hot/warm node of F2FS is not distinguished from other write_hints,
> which can make the wrong stream seperation.
> 
> * Liang, Yu, et al. "An empirical study of F2FS on mobile devices." 2017
> IEEE 23rd International Conference on Embedded and Real-Time Computing
> Systems and Applications (RTCSA).
> 
> Signed-off-by: Daejun Park <daejun7.park@...sung.com>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

Thanks,