ext4: speed-up releasing blocks on commit

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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>

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Andrey Sidorov 2013-04-09 12:22:29 -04:00 • committed by Theodore Ts'o

parent 5c1ff33640

commit eabe0444df

1 changed files with 172 additions and 61 deletions

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fs/ext4/mballoc.c

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