ffcnt 0.2.1

Fast file counting on HDDs
ffcnt-0.2.1 is not a library.

Version

ffcnt

Fast file counting and listing for spinning rust, in rust.

ffcnt's purpose is to provide a faster alternatives to some common filesystem operations as a frontend for the platter-walk crate.

  • ffcnt --type f replaces find -type f | wc -l
  • ffcnt --type f --ls --leaf-order content replaces find -type f and returns files in optimized order for reading
  • ffcnt -s replaces du -s --apparent-size

Requirements

  • Linux
  • A filesystem that supports the fiemap ioctl on directories. Currently ext4 is known to provide that. If you know other ones, please report! Incompatible filesystems will work but gain no speedup over find.

You can test filesystem support with the filefrag tool.

## supported

$ filefrag /tmp/
/tmp/: 3 extents found


## unsupported

$ filefrag /mnt/test/
/mnt/test/: FIBMAP unsupported

Binary

You can find prebuilt x86_64-linux-glibc binaries without debug information under releases. For troubleshooting and other environments you'll have to build your own.

Build

  • clone repo
  • install liblzo2 and libz (build-time dependencies)
  • install rust and cargo
  • cargo build --release

Usage

    ffcnt [FLAGS] [OPTIONS] [dirs]...

FLAGS:
    -h, --help       Prints help information
        --ls         list files
    -s               sum apparent length of matched files. Implies --leaf-order inode.
    -V, --version    Prints version information

OPTIONS:
        --leaf-order <ord>    optimize order for listing/stat/reads [values: inode, content, dentry]
        --type <type>         filter type [values: f, l, d, s, b, c, p]

ARGS:
    <dirs>...    directories to traverse [default: cwd]

Unscientific Benchmark

Idle system:

# echo 3 > /proc/sys/vm/drop_caches ; time ffcnt .
196608

real	0m23.889s
user	0m1.233s
sys	0m2.127s

# echo 3 > /proc/sys/vm/drop_caches ; time find . -type f | wc -l
196608

real	2m31.562s
user	0m0.557s
sys	0m3.860s

Busy system with mixed read/write workload. Differences in file counts arose due to writes happening in the meantime:

# echo 3 > /proc/sys/vm/drop_caches ; time ffcnt . 
4411262

real	10m36.288s
user	0m3.656s
sys	0m7.588s

# echo 3 > /proc/sys/vm/drop_caches ; time find . -type f | wc -l
4412101

real	45m54.955s
user	0m3.212s
sys	0m12.044s

Both tests were performed on HDDs and the files were spread over 65536 directories with a nesting depth of 2, i.e. a branching factor of 256.

Ideas

  • 1 thread per block device in tree