Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2] f2fs: change write_hint for hot/warm nodes | From | Chao Yu <> | Date | Thu, 5 Nov 2020 11:15:53 +0800 |
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On 2020/11/4 2:58, Jaegeuk Kim wrote: > On 11/03, 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. > > I prefer to keep it as is, since basically node blocks should be separatly > stored from data blocks in different erase blocks in order to match F2FS GC
Correct, I missed that the change will break HOT_DATA type and {HOT,WARM}_NODE type data separation in FTL.
> and FTL GC units. And, we don't do IPU for node blocks which doesn't make sense > to say *update ratio*.
IMO, if fs discard is fast enough, both IPU and OPU will cause original blkaddr in FTL being invalid, we can compare update ratio on {I,O}PU IOs inside FTL; otherwise, we can't.
Thanks,
> >> >> 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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