On Jul 22, 11:27 am, Jason Moxham <[email protected]> wrote:
> On Friday 17 July 2009 08:32:30 Cactus wrote:
>
> > On Jul 16, 11:55 pm, Jason Moxham <[email protected]> wrote:
> > > A comparison of MPIR-1.2.1 on intel nehalem built as a core2 on Linux
> > > and Windows.
>
> > > This is in cycles and first col is Linux and second col is windows ,
> > > ignore the # , they are wrong
>
> > > ./speed -c -s 1-40 mpn_add_n colfile=1,win64_bat/time_add
> > > overhead 5.71 cycles, precision 1000000 units of 3.75e-10 secs, CPU freq
> > > 2664.77 MHz
> > > mpn_add_n colfile=1,win64_bat/time_add
> > > 1 #12.38 12.38
> > > 2 #11.43 12.38
> > > 3 #13.09 13.50
> > > 4 #18.41 18.10
> > > 5 #23.81 23.81
> > > 6 #24.00 24.45
> > > 7 #27.76 27.25
> > > 8 #26.19 26.19
> > > 9 #28.42 30.00
> > > 10 #29.62 31.43
> > > 11 #32.31 32.86
> > > 12 #34.50 34.29
> > > 13 #37.39 37.14
> > > 14 #40.00 38.73
> > > 15 #41.91 42.86
> > > 16 #40.48 42.22
> > > 17 #44.77 45.72
> > > 18 #45.85 46.77
> > > 19 #48.39 48.19
> > > 20 #49.53 49.76
> > > 21 #53.66 53.53
> > > 22 #53.81 54.65
> > > 23 #55.24 56.33
> > > 24 #56.91 57.31
> > > 25 #60.48 60.96
> > > 26 #60.84 62.65
> > > 27 #62.60 63.43
> > > 28 #65.72 64.76
> > > 29 #68.58 67.46
> > > 30 #67.39 69.80
> > > 31 #72.67 69.53
> > > 32 #72.39 72.96
> > > 33 #75.72 77.15
> > > 34 #76.91 78.81
> > > 35 #76.20 78.26
> > > 36 #79.06 80.72
> > > 37 #83.34 83.43
> > > 38 #84.77 84.90
> > > 39 #85.62 85.34
> > > 40 #87.49 88.58
>
> > > ./speed -c -s 1-40 mpn_addmul_1.333 colfile=1,win64_bat/time_addmul1
> > > overhead 5.71 cycles, precision 1000000 units of 3.75e-10 secs, CPU freq
> > > 2664.77 MHz
> > > mpn_addmul_1.333 colfile=1,win64_bat/time_addmul1
> > > 1 #11.43 37.14
> > > 2 #17.15 28.33
> > > 3 #23.15 31.43
> > > 4 #29.05 39.53
> > > 5 #34.62 46.11
> > > 6 #40.52 49.23
> > > 7 #45.72 54.29
> > > 8 #51.75 57.60
> > > 9 #57.15 65.12
> > > 10 #63.09 67.21
> > > 11 #69.00 72.63
> > > 12 #74.97 75.98
> > > 13 #80.01 82.07
> > > 14 #76.77 85.72
> > > 15 #80.32 90.48
> > > 16 #84.24 94.29
> > > 17 #91.04 101.52
> > > 18 #95.12 104.77
> > > 19 #98.95 110.62
> > > 20 #103.40 114.86
> > > 21 #108.45 118.74
> > > 22 #112.95 124.58
> > > 23 #116.22 129.26
> > > 24 #120.21 133.34
> > > 25 #127.04 138.46
> > > 26 #131.78 142.97
> > > 27 #135.26 147.81
> > > 28 #140.71 152.63
> > > 29 #146.01 156.67
> > > 30 #149.29 161.39
> > > 31 #151.82 167.20
> > > 32 #157.58 171.12
> > > 33 #163.28 177.38
> > > 34 #168.20 181.00
> > > 35 #173.00 185.66
> > > 36 #176.42 191.12
> > > 37 #183.57 195.69
> > > 38 #185.68 200.07
> > > 39 #190.67 204.46
> > > 40 #191.45 209.37
>
> > > ./speed -c -s 1-40 mpn_addmul_2 colfile=1,win64_bat/time_addmul2
> > > overhead 5.71 cycles, precision 1000000 units of 3.75e-10 secs, CPU freq
> > > 2664.77 MHz
> > > mpn_addmul_2 colfile=1,win64_bat/time_addmul2
> > > 1 n/a #0.00
> > > 2 #25.10 31.82
> > > 3 #33.71 39.53
> > > 4 #41.34 49.40
> > > 5 #51.20 57.57
> > > 6 #57.15 65.53
> > > 7 #65.72 73.81
> > > 8 #74.00 81.95
> > > 9 #83.00 90.01
> > > 10 #91.31 97.15
> > > 11 #99.70 104.77
> > > 12 #108.22 115.16
> > > 13 #116.44 122.20
> > > 14 #121.93 130.01
> > > 15 #131.60 139.69
> > > 16 #139.31 147.51
> > > 17 #149.05 155.11
> > > 18 #156.21 164.43
> > > 19 #165.05 171.73
> > > 20 #172.72 180.22
> > > 21 #181.55 188.48
> > > 22 #189.37 199.52
> > > 23 #199.07 203.65
> > > 24 #206.69 212.16
> > > 25 #212.50 221.57
> > > 26 #222.27 229.50
> > > 27 #231.47 237.38
> > > 28 #238.32 246.91
> > > 29 #247.81 254.30
> > > 30 #255.24 261.65
> > > 31 #261.85 272.16
> > > 32 #271.55 279.69
> > > 33 #280.37 285.91
> > > 34 #288.60 295.80
> > > 35 #297.46 302.80
> > > 36 #304.37 311.85
> > > 37 #312.94 320.60
> > > 38 #320.62 327.36
> > > 39 #328.93 337.28
> > > 40 #338.25 343.47
>
> > > ./speed -c -s 1-40 mpn_mul_basecase colfile=1,win64_bat/time_mulbase
> > > overhead 5.71 cycles, precision 1000000 units of 3.75e-10 secs, CPU freq
> > > 2664.77 MHz
> > > mpn_mul_basecase colfile=1,win64_bat/time_mulbase
> > > 1 #9.52 8.57
> > > 2 #28.79 48.57
> > > 3 #50.85 72.54
> > > 4 #82.68 100.00
> > > 5 #114.62 135.24
> > > 6 #155.92 178.51
> > > 7 #210.50 232.87
> > > 8 #267.02 289.22
> > > 9 #341.31 438.35
> > > 10 #416.70 431.50
> > > 11 #504.12 523.84
> > > 12 #592.83 612.98
> > > 13 #698.18 727.01
> > > 14 #803.90 828.87
> > > 15 #927.52 951.48
> > > 16 #1044.89 1069.58
> > > 17 #1197.26 1222.67
> > > 18 #1328.40 1350.14
> > > 19 #1480.56 1504.67
> > > 20 #1633.17 1652.56
> > > 21 #1818.39 1838.12
> > > 22 #1988.85 2004.68
> > > 23 #2185.06 2194.37
> > > 24 #2355.79 2372.55
> > > 25 #2589.94 2599.87
> > > 26 #2769.85 2792.36
> > > 27 #2993.14 3007.09
> > > 28 #3205.00 3403.94
> > > 29 #3445.63 3475.97
> > > 30 #3678.54 3708.50
> > > 31 #3929.52 3976.62
> > > 32 #4184.47 4208.07
> > > 33 #4478.52 4500.55
> > > 34 #4726.07 4756.50
> > > 35 #5034.90 5048.47
> > > 36 #5295.16 5317.34
> > > 37 #5626.73 5646.50
> > > 38 #5902.33 5917.02
> > > 39 #6225.96 6252.33
> > > 40 #6541.47 6563.06
>
> > > ./speed -c -s 1-40 mpn_sqr_basecase colfile=1,win64_bat/time_sqrbase
> > > overhead 5.71 cycles, precision 1000000 units of 3.75e-10 secs, CPU freq
> > > 2664.77 MHz
> > > mpn_sqr_basecase colfile=1,win64_bat/time_sqrbase
> > > 1 #7.62 7.62
> > > 2 #17.14 17.14
> > > 3 #43.81 47.53
> > > 4 #74.29 85.72
> > > 5 #106.19 114.45
> > > 6 #133.83 145.72
> > > 7 #171.69 183.59
> > > 8 #213.36 223.73
> > > 9 #259.08 270.49
> > > 10 #310.52 322.39
> > > 11 #367.15 376.37
> > > 12 #426.64 439.26
> > > 13 #494.58 508.89
> > > 14 #562.71 572.72
> > > 15 #641.03 649.69
> > > 16 #713.74 728.12
> > > 17 #803.52 812.86
> > > 18 #890.97 899.63
> > > 19 #982.98 995.49
> > > 20 #1082.37 1092.61
> > > 21 #1183.96 1204.66
> > > 22 #1291.96 1300.94
> > > 23 #1405.15 1405.02
> > > 24 #1521.08 1531.02
> > > 25 #1651.29 1651.48
> > > 26 #1769.72 1778.50
> > > 27 #1895.14 1911.57
> > > 28 #2030.37 2525.85
> > > 29 #2195.53 2188.53
> > > 30 #2317.56 2333.57
> > > 31 #2470.87 2481.63
> > > 32 #2627.25 2636.25
> > > 33 #2791.54 2805.56
> > > 34 #2936.54 2958.32
> > > 35 #3118.37 3126.90
> > > 36 #3280.58 3298.26
> > > 37 #3454.08 3479.90
> > > 38 #3648.92 3655.95
> > > 39 #3844.89 3844.73
> > > 40 #4031.90 4078.56
>
> > > The very small differences between mpn_add_n on Linux and Windows show
> > > that the other differences are not just down to how we call the cpu timer
> > > or function call overheads, therefore they are real timing differences
> > > and not some artifact. So we hopefully can improve this. I would of
> > > preferred AMD timings as I am more familiar with that chip.
>
> > Hi Jason,
>
> > We have done these comparisons before and none of these figures are
> > surprising since they reflect the three different staregies that I
> > have to use for *nix to Windows assembler code conversion.
>
> > 1. If a *nix assembler function (a) doesn't use the stack, and (b) can
> > leave two scratch registers unused, it can be converted by simply
> > remapping the registers and, except for use of different registers, it
> > will be identical on *nix and Windows. This applies, for example, to
> > mpn_add_n. This is a Windows leaf function that does not need to
> > support exception handling and stack unwinding. Other conversions
> > require Windows frame functions with exception support.
>
> > 2. If not enough scratch registers are available, I have to save and
> > restore registers on the stack but when the function is simple enough
> > I can still remap the registers. This gives a constant (independent
> > of limb count) overhead.
>
> > 3. For complex functions remapping the registers can be too hard to do
> > so in such cases I save registers on the stack and then move input
> > parameters from their Windows registers to where the *nix assembler
> > expects them to be. This again gives a constant overhead, one that is
> > a bit higher than in 2 above.
>
> > To reduce the overhead in 2 it is necessary to change the assembler to
> > use fewer registers. This is becaause rsi and rdi are scratch
> > registers on *nix but not on Windows.
>
> > Some overhead can be saved on 3 by remapping registers but these are
> > functions where the overhead is typically a small proportion of the
> > functions average cost since these are generally the functions where
> > the cost is quadratic on limb count.
>
> > Brian
>
> Hi
>
> Just got my internet back , Phew...
>
> I was aware of the different methods and why , I was just surprised by the
> size of differences , it seems like the windows versions are using more
> cycles than they "should". Even for the linux code I only really concentrated
> on the inner loops , there is no point in tuning the setup code while the
> inner loops are changing. I plan to change the inner loops yet again , so
> there is little point in changing the outer code now.
Hi Jason
I wrote a Python curve fitter for speed output from all the assembler
code and it gave the right 'cost per limb' when compared with your
linux figures.
I agree that there is a constant fixed overhead for the extar Windows
operations but it didn't seem unusually high when I looked at it -
admittedly some time ago.
Brian
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