Val,
Do you remember this patch:
[PATCH] Make EXT2_DEBUG work again
http://www.kernel.org/git/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=21730eed11de42f22afcbd43f450a1872a0b5ea1
The second part causes a 30% performance degradation running dbench with
16 threads.
> Second, debug versions of ext2_count_free_{inodes/blocks} reacquires
> superblock lock. Moved lock into callers.
The problem is that before your patch, the superblock lock was taken
only when EXT2_DEBUG was enabled, but with your patch, the superblock
lock is held during the entire call to ext2_statfs() with our without
EXT2_DEBUG defined.
Was there a reason the lock needed to be held across both calls? Since
the patch didn't mention fixing the non-debug case, I assume the lack of
the lock in the non-debug case was okay.
--
David Kleikamp
IBM Linux Technology Center