[PATCH 0/5] Make filesystem shrinking faster and less CPU-intensive

Sami Liedes <sami.liedes@xxxxxx> · Sat, 10 Mar 2012 23:33:21 +0200

This patch set speeds up at least resize2fs shrinking by causing its
CPU usage to drop by 99.5% by optimizing inode bitfield scanning.

Test case: A 100G ext4 filesystem filled to 50% with copies of
/usr/share/doc, shrinking to 75G on a slow disk (~5400 rpm) and fast
processor (Core i7):

Before:

# time resize2fs -p $FILESYSTEM 75G
[...]
real    96m26.852s
user    56m39.768s
sys     0m27.922s

After:

# time resize2fs -p $FILESYSTEM 75G
real    39m49.287s
user    0m16.601s
sys     0m26.606s

Sami Liedes (5):
      libext2fs: Move a modulo operation out of a hot loop.
      resize2fs: Use EXT2_FLAG_64BITS.
      libext2fs: Document EXT2_FLAG_64BITS in ext2fs_open2().
      libext2fs: Implement ext2fs_find_first_zero_generic_bmap().
      libext2fs: Implement fast find_first_zero() for bitarray bitmaps.

 lib/ext2fs/alloc.c        |   27 +++------------
 lib/ext2fs/bitops.h       |   16 ---------
 lib/ext2fs/blkmap64_ba.c  |   81 ---------------------------------------------
 lib/ext2fs/bmap64.h       |    5 ---
 lib/ext2fs/gen_bitmap64.c |   28 ---------------
 lib/ext2fs/openfs.c       |    1 -
 resize/main.c             |    3 --
 7 files changed, 5 insertions(+), 156 deletions(-)
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