From: Andrey Sidorov <qrxd43@motorola.com>
Date: Tue, 9 Apr 2013 16:22:29 +0000 (-0400)
Subject: ext4: speed-up releasing blocks on commit
X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~83^2~28
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eabe0444df90b0cdfa7fdc4f0b4b253f0a498ff7;p=pandora-kernel.git

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>
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