diff options
| author | Gao Xiang <[email protected]> | 2019-06-24 15:22:51 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <[email protected]> | 2019-06-26 09:44:39 +0800 |
| commit | ec8c24420501d4cf3ed495c4d026984194897276 (patch) | |
| tree | 9ecde9f14e9b774cd311059f78e710afe756b816 /tools/perf/scripts/python | |
| parent | e36472145aa706c186a6bb4f6419c613b0b1305c (diff) | |
staging: erofs: add compacted ondisk compression indexes
This patch introduces new compacted compression indexes.
In contract to legacy compression indexes that
each 4k logical cluster has an 8-byte index,
compacted ondisk compression indexes will have
amortized 2 bytes for each 4k logical cluster (compacted 2B)
amortized 4 bytes for each 4k logical cluster (compacted 4B)
In detail, several continuous clusters will be encoded in
a compacted pack with cluster types, offsets, and one blkaddr
at the end of the pack to leave 4-byte margin for better
decoding performance, as illustrated below:
_____________________________________________
|___@_____ encoded bits __________|_ blkaddr _|
0 . amortized * vcnt
. .
. . amortized * vcnt - 4
. .
.___________________.
|_type_|_clusterofs_|
Note that compacted 2 / 4B should be aligned with 32 / 8 bytes
in order to avoid each pack crossing page boundary.
Reviewed-by: Chao Yu <[email protected]>
Signed-off-by: Gao Xiang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Diffstat (limited to 'tools/perf/scripts/python')
0 files changed, 0 insertions, 0 deletions