Messages in this thread Patch in this message | | | Subject | [f2fs-dev] [PATCH] f2fs: change write_hint for hot/warm nodes | From | Daejun Park <> | Date | Tue, 03 Nov 2020 15:40:39 +0900 |
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From 818a76a9aee5bf225565264274d211edb07bae7d Mon Sep 17 00:00:00 2001 From: Daejun Park <daejun7.park@samsung.com> Date: Tue, 3 Nov 2020 15:30:26 +0900
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@samsung.com> --- fs/f2fs/segment.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 1596502f7375..7b42bb10c6c3 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -3208,7 +3208,7 @@ enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi, return WRITE_LIFE_EXTREME; } else if (type == NODE) { if (temp == WARM || temp == HOT) - return WRITE_LIFE_NOT_SET; + return WRITE_LIFE_SHORT; else if (temp == COLD) return WRITE_LIFE_NONE; } else if (type == META) { -- 2.25.1
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