World: r3wp
[Profiling] Rebol code optimisation and algorithm comparisons.
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Maxim 2-Jun-2010 [435] | Its also possible that MS compilers are better at optimisation on intel CPUs than Apple. |
Ladislav 2-Jun-2010 [436x5] | Peter, I obtain the same value when running XP in the VirtualBox: >> include %timblk.r == 9.93798449612403E-3 |
>> time-block [] 0,05 == 7.97957181930542E-9 | |
>> time-block [now/precise] 0,05 == 2.11906433105469E-6 | |
so, the time granularity of XP running in VirtualBox looks smaller, than when running natively | |
funny | |
PeterWood 2-Jun-2010 [441] | From a quick browse of the Virtual Box User Manual, a VM uses the host systems "time stamp counter" by default. There are a number of options to change the "guest clock". It's section 9.10 in the Virtual Box User Manual if you want to take a look. |
Davide 2-Jun-2010 [442] | >> time-block [now/precise] 0,05 == 2.328125E-6 |
Gabriele 3-Jun-2010 [443x4] | >> time-block [now/precise] 0,05 == 2.43203125E-5 >> time-block [now/precise] 0,05 == 1.526171875E-5 >> time-block [now/precise] 0,05 == 2.44140625E-5 >> time-block [now/precise] 0,05 == 2.42890625E-5 >> time-block [now/precise] 0,05 == 2.4203125E-5 >> time-block [now/precise] 0,05 == 2.4265625E-5 |
>> time-block [] 0,05 == 1.11503601074219E-8 >> time-block [] 0,05 == 1.11885070800781E-8 >> time-block [] 0,05 == 1.11618041992188E-8 >> time-block [] 0,05 == 1.12886428833008E-8 | |
Max: scratch your theory, this is Linux running on an iMac 24" | |
(btw, i guess Linux is doing timezone conversion in the time system calls, while osx is not, and that would explain the huge difference in speed.) | |
BrianH 4-Jun-2010 [447] | Steeve, could you submit your CureCode #574 DP function to DevBase? Or can I? Good work, and it uses well features introduced to R3 since DP was originally written. We would do well to have this function :) |
Steeve 4-Jun-2010 [448] | As you wish Brianh |
Maxim 27-Jan-2011 [449] | some things are stunningly non-obvious when it comes time to optimize REBOL >> a: 1x1 b: 10x10 s: now/precise loop 1000000 [second b - a] difference now/precise s == 0:00:00.5 >> a: 1x1 b: 10x10 s: now/precise loop 1000000 [b/y - a/y] difference now/precise s == 0:00:00.969 |
Henrik 27-Jan-2011 [450] | so, pair refinements are slow? |
Maxim 27-Jan-2011 [451x2] | all path access is slow...but I woudn't have thought that using a series function and multiplying both values in the pair would be twice as fast! |
in my mind it would have been roughly equivalent. | |
Henrik 27-Jan-2011 [453] | that's very interesting for DRAW blocks. I wonder if R3 has the same issue. |
Maxim 27-Jan-2011 [454x3] | just tried it... A100 in R3 they *are* roughly equivalent :-) in fact in R3 the second version is ~ 10% FASTER ! |
so, claims that the path access is faster in R3 seems to be true across the board | |
btw the first version is exaclty the same speed as in R2, on my system. | |
Steeve 27-Jan-2011 [457x2] | I don't use first, second, third .... anymore in R3. |
when I have the choice, indeed | |
Maxim 27-Jan-2011 [459:last] | yeah, its much easier to read. I only use first/second in R2 because their faster. |
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