Ok, so why in std.parallelism examples are this :
// Same thing, but use the default work unit size.
//
// Timings on an Athlon 64 X2 dual core machine:
//
// Parallel foreach: 388 milliseconds
// Regular foreach: 619 milliseconds
foreach(i, ref elem; taskPool.parallel(logs)) {
elem = log(i + 1.0);
}
Plus, a change my code to make that for same elem, calc log 100000 times in
each loop, and now I get parallel foreach get a bit shorter time that normal
foreach....
Change code :
auto logs = new double[200];
const num = 2;
clock_t clk;
double norm;
double par;
writeln("CPUs : ",totalCPUs );
foreach (t; 0..num) {
foreach(i, ref elem; logs) {
foreach(p; 0..100_000)
elem = log(i + 1.0);
}
}
norm = clock() -clk;
clk = clock();
foreach (t; 0..num) {
foreach(i, ref elem; taskPool.parallel(logs, 100)) {
foreach(p; 0..100_000)
elem = log(i + 1.0);
}
}
New times : Normal : 12.725 Parallel : 12.499
