Messages in this thread Patch in this message | | | Subject | [PATCH v2] f2fs: change write_hint for hot/warm nodes | From | Daejun Park <> | Date | Tue, 03 Nov 2020 17:38:32 +0900 |
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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> --- v2: update documentation and comments --- Documentation/filesystems/f2fs.rst | 4 ++-- fs/f2fs/segment.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index b8ee761c9922..afa3da7cfade 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -717,8 +717,8 @@ WRITE_LIFE_LONG " WRITE_LIFE_LONG ===================== ======================== =================== User F2FS Block ===================== ======================== =================== - META WRITE_LIFE_MEDIUM; - HOT_NODE WRITE_LIFE_NOT_SET + META WRITE_LIFE_MEDIUM + HOT_NODE WRITE_LIFE_SHORT WARM_NODE " COLD_NODE WRITE_LIFE_NONE ioctl(COLD) COLD_DATA WRITE_LIFE_EXTREME diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 1596502f7375..577ab7516c6b 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -3160,8 +3160,8 @@ int f2fs_rw_hint_to_seg_type(enum rw_hint hint) * * User F2FS Block * ---- ---- ----- - * META WRITE_LIFE_MEDIUM; - * HOT_NODE WRITE_LIFE_NOT_SET + * META WRITE_LIFE_MEDIUM + * HOT_NODE WRITE_LIFE_SHORT * WARM_NODE " * COLD_NODE WRITE_LIFE_NONE * ioctl(COLD) COLD_DATA WRITE_LIFE_EXTREME @@ -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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