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35a82d1a53
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Nick Piggin 35a82d1a53 [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>
2005-06-23 09:45:18 -07:00
..
acpi
asm-alpha [PATCH] remove non-DISCONTIG use of pgdat->node_mem_map 2005-06-23 09:45:00 -07:00
asm-arm Merge master.kernel.org:/home/rmk/linux-2.6-arm 2005-06-22 14:51:06 -07:00
asm-arm26 [PATCH] Remove obsolete HAVE_ARCH_GET_SIGNAL_TO_DELIVER? 2005-06-12 20:43:21 -07:00
asm-cris [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
asm-frv [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
asm-generic [PATCH] x86/x86_64: pcibus_to_node 2005-06-23 09:45:08 -07:00
asm-h8300 [PATCH] h8300 build error fix 2005-06-06 14:42:23 -07:00
asm-i386 [PATCH] xen: x86: Rename usermode macro 2005-06-23 09:45:14 -07:00
asm-ia64 [PATCH] ia64: Selectable Timer Interrupt Frequency 2005-06-23 09:45:10 -07:00
asm-m32r [PATCH] m32r: build fix for asm-m32r/topology.h 2005-06-23 09:45:08 -07:00
asm-m68k [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
asm-m68knommu [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
asm-mips [PATCH] mips: add vr41xx gpio support 2005-06-21 18:46:32 -07:00
asm-parisc [PATCH] remove non-DISCONTIG use of pgdat->node_mem_map 2005-06-23 09:45:00 -07:00
asm-ppc [PATCH] ppc32: Clean up NUM_TLBCAMS usage for Freescale Book-E PPC's 2005-06-21 18:46:24 -07:00
asm-ppc64 [PATCH] ppc64: pcibus_to_node fix 2005-06-23 09:45:08 -07:00
asm-s390 [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
asm-sh [PATCH] Hugepage consolidation 2005-06-21 18:46:15 -07:00
asm-sh64 [PATCH] Hugepage consolidation 2005-06-21 18:46:15 -07:00
asm-sparc [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
asm-sparc64 [PATCH] Hugepage consolidation 2005-06-21 18:46:15 -07:00
asm-um [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
asm-v850 [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
asm-x86_64 [PATCH] xen: x86_64: Add macro for debugreg 2005-06-23 09:45:14 -07:00
linux [PATCH] optimise loop driver a bit 2005-06-23 09:45:18 -07:00
math-emu
media [PATCH] dvb: modified dvb_register_adapter() to avoid kmalloc/kfree 2005-05-17 07:59:33 -07:00
mtd
net [X25]: Fast select with no restriction on response 2005-06-22 22:16:17 -07:00
pcmcia
rxrpc
scsi Automatic merge of ../scsi-misc-2.6-old/ 2005-05-26 14:14:55 -04:00
sound [PATCH] create a kstrdup library function 2005-06-23 09:45:18 -07:00
video