[PATCH 3/3] erofs-utils: introduce fragment cache

[Gao Xiang]

On 2025/1/17 15:46, Gao Xiang wrote:
> Difference from the previous Yiyan's version [1], it just uses
> a tmpfile to keep all decompressed data for fragments.
> 
> Dataset: linux 5.4.140
> mkfs.erofs command line:
> 	mkfs.erofs -zlzma -C131072 -T0 -Eall-fragments,fragdedupe=inode foo.erofs <dir>
> Test command line:
> 	hyperfine -p "echo 3 > /proc/sys/vm/drop_caches; sleep 1" "fsck/fsck.erofs --extract foo.erofs"
> 
> Vanilla:
>    Time (mean ± σ):     362.309 s ±  0.406 s   [User: 360.298 s, System: 0.956 s]
> 
> After:
>    Time (mean ± σ):     20.880 s ±  0.026 s    [User: 19.751 s, System: 1.058 s]

An in-memory LRU cache could also be implemented later to
meet different needs.

> 
> [1] https://lore.kernel.org/r/20231023071528.1912105-1-lyy0627@sjtu.edu.cn
> Cc: Li Yiyan <lyy0627 at sjtu.edu.cn>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>