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Postings from December 2016
I just pushed a patch which optimises our hash function somewhat by
using a hybrid approach, with an optimised OAATH for short keys (16
bytes or less), and Siphash 1-3, for the rest.
For longer keys, say 50 byte or up, Siphash 1-3 makes a big
difference. By the time you get to 1k keys or longer it makes a HUGE
difference.
For shorter keys I unrolled the OAATH logic so it doesn't have so much
overhead. The new OAATH code is a touch different in that it hashes
back to front.
32 bit builds should be unchanged, and continue to use the previous OAATH logic.
Siphash 1-3 is used by Rust, and is faster than Siphash 2-4, while
still being "secure enough".
BTW, I apologise for pushing this without a smoke round, I got a
little fast-finger-memory and pushed to blead when I should have
pushed to a branch. Normally I would have discussed this a bit wider
first.
Here are the timings from the change using Porting/bench.pl for keys
of length 1..24, 50, 100, and 1000. I believe most keys in a process
are short, hence the bias in the benchmarks.
The numbers represent relative counts per loop iteration, compared to
blead at 100.0%.
Higher is better: for example, using half as many instructions gives 200%,
while using twice as many gives 50%.
hash::set1k::len_0001
hash keys length 1
blead yves
------ ------
Ir 100.00 100.75
Dr 100.00 101.08
Dw 100.00 101.70
COND 100.00 101.61
IND 100.00 75.04
COND_m 100.00 97.92
IND_m 100.00 70.00
Ir_m1 100.00 4450.00
Dr_m1 100.00 100.09
Dw_m1 100.00 99.42
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0002
hash keys length 2
blead yves
------ ------
Ir 100.00 100.76
Dr 100.00 101.10
Dw 100.00 101.72
COND 100.00 101.64
IND 100.00 75.05
COND_m 100.00 99.39
IND_m 100.00 77.78
Ir_m1 100.00 4450.00
Dr_m1 100.00 100.07
Dw_m1 100.00 99.46
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0003
hash keys length 3
blead yves
------ ------
Ir 100.00 100.94
Dr 100.00 101.30
Dw 100.00 102.05
COND 100.00 102.05
IND 100.00 75.06
COND_m 100.00 101.72
IND_m 100.00 100.00
Ir_m1 100.00 1950.00
Dr_m1 100.00 99.78
Dw_m1 100.00 99.76
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0004
hash keys length 4
blead yves
------ ------
Ir 100.00 101.24
Dr 100.00 101.64
Dw 100.00 102.57
COND 100.00 102.74
IND 100.00 75.06
COND_m 100.00 100.66
IND_m 100.00 100.00
Ir_m1 100.00 1950.00
Dr_m1 100.00 99.40
Dw_m1 100.00 99.24
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0005
hash keys length 5
blead yves
------ ------
Ir 100.00 101.52
Dr 100.00 101.95
Dw 100.00 103.07
COND 100.00 103.43
IND 100.00 75.06
COND_m 100.00 95.62
IND_m 100.00 100.00
Ir_m1 100.00 1950.00
Dr_m1 100.00 99.66
Dw_m1 100.00 100.01
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0006
hash keys length 6
blead yves
------ ------
Ir 100.00 101.84
Dr 100.00 102.31
Dw 100.00 103.61
COND 100.00 104.12
IND 100.00 75.06
COND_m 100.00 102.58
IND_m 100.00 100.00
Ir_m1 100.00 1950.00
Dr_m1 100.00 100.18
Dw_m1 100.00 99.03
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0007
hash keys length 7
blead yves
------ ------
Ir 100.00 102.18
Dr 100.00 102.70
Dw 100.00 104.14
COND 100.00 104.94
IND 100.00 75.06
COND_m 100.00 100.29
IND_m 100.00 100.00
Ir_m1 100.00 93.98
Dr_m1 100.00 99.75
Dw_m1 100.00 99.09
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0008
hash keys length 8
blead yves
------ ------
Ir 100.00 102.40
Dr 100.00 102.93
Dw 100.00 104.63
COND 100.00 105.51
IND 100.00 75.06
COND_m 100.00 140.83
IND_m 100.00 100.00
Ir_m1 100.00 93.98
Dr_m1 100.00 99.40
Dw_m1 100.00 99.97
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0009
hash keys length 9
blead yves
------ ------
Ir 100.00 102.69
Dr 100.00 103.25
Dw 100.00 105.15
COND 100.00 106.24
IND 100.00 75.06
COND_m 100.00 140.16
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 99.93
Dw_m1 100.00 99.92
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0010
hash keys length 10
blead yves
------ ------
Ir 100.00 102.97
Dr 100.00 103.56
Dw 100.00 105.67
COND 100.00 106.94
IND 100.00 75.06
COND_m 100.00 146.64
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 99.82
Dw_m1 100.00 98.65
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0011
hash keys length 11
blead yves
------ ------
Ir 100.00 103.29
Dr 100.00 103.92
Dw 100.00 106.20
COND 100.00 107.72
IND 100.00 75.06
COND_m 100.00 144.43
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 100.20
Dw_m1 100.00 100.69
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0012
hash keys length 12
blead yves
------ ------
Ir 100.00 103.68
Dr 100.00 104.38
Dw 100.00 106.78
COND 100.00 108.64
IND 100.00 75.06
COND_m 100.00 154.50
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 100.61
Dw_m1 100.00 99.20
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0013
hash keys length 13
blead yves
------ ------
Ir 100.00 103.93
Dr 100.00 104.64
Dw 100.00 107.29
COND 100.00 109.32
IND 100.00 75.06
COND_m 100.00 150.58
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 101.69
Dw_m1 100.00 99.82
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0014
hash keys length 14
blead yves
------ ------
Ir 100.00 104.05
Dr 100.00 104.72
Dw 100.00 107.73
COND 100.00 109.76
IND 100.00 75.06
COND_m 100.00 147.02
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 100.09
Dw_m1 100.00 98.94
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0015
hash keys length 15
blead yves
------ ------
Ir 100.00 104.32
Dr 100.00 105.01
Dw 100.00 108.26
COND 100.00 110.48
IND 100.00 75.06
COND_m 100.00 145.46
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 100.46
Dw_m1 100.00 99.48
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0016
hash keys length 16
blead yves
------ ------
Ir 100.00 104.54
Dr 100.00 105.23
Dw 100.00 108.76
COND 100.00 111.09
IND 100.00 75.06
COND_m 100.00 139.15
IND_m 100.00 100.00
Ir_m1 100.00 47.85
Dr_m1 100.00 99.75
Dw_m1 100.00 99.67
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0017
hash keys length 17
blead yves
------ ------
Ir 100.00 100.44
Dr 100.00 96.60
Dw 100.00 100.49
COND 100.00 108.85
IND 100.00 75.06
COND_m 100.00 146.97
IND_m 100.00 100.00
Ir_m1 100.00 2600.00
Dr_m1 100.00 100.34
Dw_m1 100.00 99.26
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0018
hash keys length 18
blead yves
------ ------
Ir 100.00 100.96
Dr 100.00 97.36
Dw 100.00 100.92
COND 100.00 109.35
IND 100.00 75.06
COND_m 100.00 139.74
IND_m 100.00 100.00
Ir_m1 100.00 2600.00
Dr_m1 100.00 98.65
Dw_m1 100.00 99.59
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0019
hash keys length 19
blead yves
------ ------
Ir 100.00 101.58
Dr 100.00 98.26
Dw 100.00 101.41
COND 100.00 110.04
IND 100.00 75.06
COND_m 100.00 140.42
IND_m 100.00 100.00
Ir_m1 100.00 2600.00
Dr_m1 100.00 99.49
Dw_m1 100.00 100.01
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0020
hash keys length 20
blead yves
------ ------
Ir 100.00 102.22
Dr 100.00 99.18
Dw 100.00 101.91
COND 100.00 110.86
IND 100.00 75.06
COND_m 100.00 144.08
IND_m 100.00 100.00
Ir_m1 100.00 3900.00
Dr_m1 100.00 100.11
Dw_m1 100.00 99.57
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0021
hash keys length 21
blead yves
------ ------
Ir 100.00 102.85
Dr 100.00 100.08
Dw 100.00 102.40
COND 100.00 111.61
IND 100.00 75.06
COND_m 100.00 147.80
IND_m 100.00 100.00
Ir_m1 100.00 3900.00
Dr_m1 100.00 101.66
Dw_m1 100.00 100.23
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0022
hash keys length 22
blead yves
------ ------
Ir 100.00 103.41
Dr 100.00 100.89
Dw 100.00 102.87
COND 100.00 112.24
IND 100.00 75.06
COND_m 100.00 146.65
IND_m 100.00 100.00
Ir_m1 100.00 3900.00
Dr_m1 100.00 100.29
Dw_m1 100.00 99.47
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0023
hash keys length 23
blead yves
------ ------
Ir 100.00 103.97
Dr 100.00 101.70
Dw 100.00 103.33
COND 100.00 112.88
IND 100.00 75.06
COND_m 100.00 143.60
IND_m 100.00 100.00
Ir_m1 100.00 2600.00
Dr_m1 100.00 101.03
Dw_m1 100.00 99.85
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0024
hash keys length 24
blead yves
------ ------
Ir 100.00 102.44
Dr 100.00 99.50
Dw 100.00 103.26
COND 100.00 112.60
IND 100.00 75.06
COND_m 100.00 137.30
IND_m 100.00 100.00
Ir_m1 100.00 1950.00
Dr_m1 100.00 100.07
Dw_m1 100.00 99.68
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0050
hash keys length 50
blead yves
------ ------
Ir 100.00 110.70
Dr 100.00 110.30
Dw 100.00 113.87
COND 100.00 127.62
IND 100.00 75.06
COND_m 100.00 148.43
IND_m 100.00 100.00
Ir_m1 100.00 3900.00
Dr_m1 100.00 100.65
Dw_m1 100.00 99.66
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_0100
hash keys length 100
blead yves
------ ------
Ir 100.00 119.81
Dr 100.00 122.37
Dw 100.00 128.53
COND 100.00 147.72
IND 100.00 75.06
COND_m 100.00 99.89
IND_m 100.00 100.00
Ir_m1 100.00 913.70
Dr_m1 100.00 99.58
Dw_m1 100.00 100.08
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
hash::set1k::len_1000
hash keys length 1000
blead yves
------ ------
Ir 100.00 147.57
Dr 100.00 151.97
Dw 100.00 294.09
COND 100.00 330.60
IND 100.00 75.23
COND_m 100.00 100.60
IND_m 100.00 100.00
Ir_m1 100.00 560.33
Dr_m1 100.00 100.05
Dw_m1 100.00 99.98
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
AVERAGE
blead yves
------ ------
Ir 100.00 104.47
Dr 100.00 103.97
Dw 100.00 107.63
COND 100.00 112.16
IND 100.00 75.07
COND_m 100.00 125.75
IND_m 100.00 97.42
Ir_m1 100.00 137.11
Dr_m1 100.00 100.10
Dw_m1 100.00 99.62
Ir_mm 100.00 100.00
Dr_mm 100.00 100.00
Dw_mm 100.00 100.00
Yves
--
perl -Mre=debug -e "/just|another|perl|hacker/"
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