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Use the x86 cache-bypassing copy instructions for copy_from_user().
Some performance data are
Total of GLOBAL_POWER_EVENTS (CPU cycle samples)
2.6.12.4.orig 1921587
2.6.12.4.nt 1599424
1599424/1921587=83.23% (16.77% reduction)
BSQ_CACHE_REFERENCE (L3 cache miss)
2.6.12.4.orig 57427
2.6.12.4.nt 20858
20858/57427=36.32% (63.7% reduction)
L3 cache miss reduction of __copy_from_user_ll
samples %
37408 65.1412 vmlinux __copy_from_user_ll
23 0.1103 vmlinux __copy_user_zeroing_intel_nocache
23/37408=0.061% (99.94% reduction)
Top 5 of 2.6.12.4.nt
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
samples % app name symbol name
128392 8.0274 vmlinux __copy_user_zeroing_intel_nocache
64206 4.0143 vmlinux journal_add_journal_head
59746 3.7355 vmlinux do_get_write_access
47674 2.9807 vmlinux journal_put_journal_head
46021 2.8774 vmlinux journal_dirty_metadata
pattern9-0-cpu4-0-09011728/summary.out
Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x3f (multiple flags) count 3000
samples % app name symbol name
69755 4.2861 vmlinux __copy_user_zeroing_intel_nocache
55685 3.4215 vmlinux journal_add_journal_head
52371 3.2179 vmlinux __find_get_block
45504 2.7960 vmlinux journal_put_journal_head
36005 2.2123 vmlinux journal_stop
pattern9-0-cpu4-0-09011744/summary.out
Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x200 (read 3rd level cache miss) count 3000
samples % app name symbol name
1147 5.4994 vmlinux journal_add_journal_head
881 4.2240 vmlinux journal_dirty_data
872 4.1809 vmlinux blk_rq_map_sg
734 3.5192 vmlinux journal_commit_transaction
617 2.9582 vmlinux radix_tree_delete
pattern9-0-cpu4-0-09011731/summary.out
iozone results are
original 2.6.12.4 CPU time = 207.768 sec
cache aware CPU time = 184.783 sec
(three times run)
184.783/207.768=88.94% (11.06% reduction)
original:
pattern9-0-cpu4-0-08191720/iozone.out: CPU Utilization: Wall time 45.997 CPU time 64.527 CPU utilization 140.28 %
pattern9-0-cpu4-0-08191741/iozone.out: CPU Utilization: Wall time 46.878 CPU time 71.933 CPU utilization 153.45 %
pattern9-0-cpu4-0-08191743/iozone.out: CPU Utilization: Wall time 45.152 CPU time 71.308 CPU utilization 157.93 %
cache awre:
pattern9-0-cpu4-0-09011728/iozone.out: CPU Utilization: Wall time 44.842 CPU time 62.465 CPU utilization 139.30 %
pattern9-0-cpu4-0-09011731/iozone.out: CPU Utilization: Wall time 44.718 CPU time 59.273 CPU utilization 132.55 %
pattern9-0-cpu4-0-09011744/iozone.out: CPU Utilization: Wall time 44.367 CPU time 63.045 CPU utilization 142.10 %
Signed-off-by: Hiro Yoshioka <hyoshiok@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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