On Wednesday, 6 April 2016 at 18:54:08 UTC, tsbockman wrote:
On Wednesday, 6 April 2016 at 08:15:39 UTC, Andrea Fontana
wrote:
Using ldmd2 -O -release -noboundscheck -inline sort.d && ./sort
instead:
2 inputs:
Faster: 0 hnsecs
Phobos: 33 μs and 5 hnsecs
...
65536 inputs:
Faster: 0 hnsecs (???)
Phobos: 7 secs, 865 ms, 450 μs, and 6 hnsecs
Can you share the benchmark code?
"0 hnsecs" results generally mean that your test was too simple
and/or didn't have any obvious side effects, and so the
optimizer just removed it completely.
A simple test just written:
Duration total;
foreach(_; 0..10000)
{
auto arr = generate!( () => uniform(0,2)).map!(x =>
cast(bool)x).take(65536).array;
StopWatch sw;
sw.start;
boolSort(arr);
total += sw.peek.to!Duration;
sw.stop;
}
andrea@ububocs:/tmp$ ./sort
0 hnsecs
I don't think compiler can remove a random generated array...
I think times are too small to be measured with a good accuracy,
using start() stop() to resume stopwatch seems to add a (fixed)
overhead (some microsecs over the 10000 cycles) that doesn't
depend on size of array tested.
Anyway, it doesn't matter if it is 0 hnsec or some microsecs, in
my opinion. It's still faster and faster than original sort (of
course it's n vs n*log(n)). Here the same code with "sort(arr)"
instead of "boolSort(arr)":
andrea@ububocs:/tmp$ ./sort
10 secs, 620 ms, 414 μs, and 2 hnsecs
Andrea
