Revert "ext2/ext3/ext4: add block bitmap validation"
authorLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 13 Nov 2007 16:07:31 +0000 (08:07 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Tue, 13 Nov 2007 16:09:11 +0000 (08:09 -0800)
commit0b832a4b93932103d73c0c3f35ef1153e288327b
tree77ca1ff445287685dbebf448fdf172d3f951ed89
parent325d22df7b19e0116aff3391d3a03f73d0634ded
Revert "ext2/ext3/ext4: add block bitmap validation"

This reverts commit 7c9e69faa28027913ee059c285a5ea8382e24b5d, fixing up
conflicts in fs/ext4/balloc.c manually.

The cost of doing the bitmap validation on each lookup - even when the
bitmap is cached - is absolutely prohibitive.  We could, and probably
should, do it only when adding the bitmap to the buffer cache.  However,
right now we are better off just reverting it.

Peter Zijlstra measured the cost of this extra validation as a 85%
decrease in cached iozone, and while I had a patch that took it down to
just 17% by not being _quite_ so stupid in the validation, it was still
a big slowdown that could have been avoided by just doing it right.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andreas Dilger <adilger@clusterfs.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/ext2/balloc.c
fs/ext3/balloc.c
fs/ext4/balloc.c