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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-06-23 03:09:06 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-23 12:45:18 -0400 |
| commit | 35a82d1a53e1a9ad54efafcc940f9335beaed5c3 (patch) | |
| tree | 776d5b01970c5ce3e2c9fd4a2c4cf2168a0afa3c /include/linux/joystick.h | |
| parent | ab4af03a4054bd78bcabfb2214c9597201beae35 (diff) | |
[PATCH] optimise loop driver a bit
Looks like locking can be optimised quite a lot. Increase lock widths
slightly so lo_lock is taken fewer times per request. Also it was quite
trivial to cover lo_pending with that lock, and remove the atomic
requirement. This also makes memory ordering explicitly correct, which is
nice (not that I particularly saw any mem ordering bugs).
Test was reading 4 250MB files in parallel on ext2-on-tmpfs filesystem (1K
block size, 4K page size). System is 2 socket Xeon with HT (4 thread).
intel:/home/npiggin# umount /dev/loop0 ; mount /dev/loop0 /mnt/loop ; /usr/bin/time ./mtloop.sh
Before:
0.24user 5.51system 0:02.84elapsed 202%CPU (0avgtext+0avgdata 0maxresident)k
0.19user 5.52system 0:02.88elapsed 198%CPU (0avgtext+0avgdata 0maxresident)k
0.19user 5.57system 0:02.89elapsed 198%CPU (0avgtext+0avgdata 0maxresident)k
0.22user 5.51system 0:02.90elapsed 197%CPU (0avgtext+0avgdata 0maxresident)k
0.19user 5.44system 0:02.91elapsed 193%CPU (0avgtext+0avgdata 0maxresident)k
After:
0.07user 2.34system 0:01.68elapsed 143%CPU (0avgtext+0avgdata 0maxresident)k
0.06user 2.37system 0:01.68elapsed 144%CPU (0avgtext+0avgdata 0maxresident)k
0.06user 2.39system 0:01.68elapsed 145%CPU (0avgtext+0avgdata 0maxresident)k
0.06user 2.36system 0:01.68elapsed 144%CPU (0avgtext+0avgdata 0maxresident)k
0.06user 2.42system 0:01.68elapsed 147%CPU (0avgtext+0avgdata 0maxresident)k
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/joystick.h')
0 files changed, 0 insertions, 0 deletions