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.p...@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
