Re: math.log() benchmark of first 1 billion int using std.parallelism

[Daniel Kozak via Digitalmars-d-learn]

On Tuesday, 23 December 2014 at 12:31:47 UTC, Iov Gherman wrote:

Btw. I just noticed small issue with D vs. java, you start 
messure in D before allocation, but in case of Java after 
allocation

Here is the java result for parallel processing after moving 
the start time as the first line in main. Still best result:

4 secs, 50 ms average

Java:

Exec time: 6 secs, 421 ms

LDC (-O3 -release -mcpu=native -singleobj -inline 
-boundscheck=off)

time: 5 secs, 321 ms, 877 μs, and 2 hnsecs

GDC(-O3 -frelease -march=native -finline -fno-bounds-check)

time: 5 secs, 237 ms, 453 μs, and 7 hnsecs

DMD(-O -release -inline -noboundscheck)
time: 5 secs, 107 ms, 931 μs, and 3 hnsecs

So all d compilers beat Java in my case:

but I have made some change in D version:

import std.parallelism, std.math, std.stdio, std.datetime;
import core.memory;

enum XMS = 3*1024*1024*1024; //3GB

version(GNU)
{
        real mylog(double x) pure nothrow
        {
                double result;
                double y = LN2;
                asm
                {
                        "fldl   %2\n"
                        "fldl   %1\n"
                        "fyl2x\n"
                        : "=t" (result) : "m" (x), "m" (y);
                }
                
                return result;
        }
}
else
{
        real mylog(double x) pure nothrow
        {
                return yl2x(x, LN2);
        }
}

void main() {

        GC.reserve(XMS);
        auto t1 = Clock.currTime();


        auto logs = new double[1_000_000_000];  
        foreach(i, ref elem; taskPool.parallel(logs, 200)) {
                elem = mylog(i + 1.0);
        }


        auto t2 = Clock.currTime();
        writeln("time: ", (t2 - t1)); 
}