ext4: speed-up releasing blocks on commit
authorAndrey Sidorov <qrxd43@motorola.com>
Tue, 9 Apr 2013 16:22:29 +0000 (12:22 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Tue, 9 Apr 2013 16:22:29 +0000 (12:22 -0400)
commiteabe0444df90b0cdfa7fdc4f0b4b253f0a498ff7
treecde3d8ee1419d56910ca3fb34745124c880ac2d4
parent5c1ff33640293499f9b16450029c9fb4dc06543e
ext4: speed-up releasing blocks on commit

Improve mb_free_blocks speed by clearing entire range at once instead
of iterating over each bit. Freeing block-by-block also makes buddy
bitmap subtree flip twice making most of the work a no-op. Very few
bits in buddy bitmap require change, e.g. freeing entire group is a 1
bit flip only.  As a result, releasing blocks of 60G file now takes
5ms instead of 2.7s.  This is especially good for non-preemptive
kernels as there is no rescheduling during release.

Signed-off-by: Andrey Sidorov <qrxd43@motorola.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
fs/ext4/mballoc.c