On Wed, 22 Dec 2010 17:04:21 -0500, Andreas Mayer <s...@bacon.eggs> wrote:
To see what performance advantage D would give me over using a scripting
language, I made a small benchmark. It consists of this code:
auto L = iota(0.0, 10000000.0);
auto L2 = map!"a / 2"(L);
auto L3 = map!"a + 2"(L2);
auto V = reduce!"a + b"(L3);
It runs in 281 ms on my computer.
The same code in Lua (using LuaJIT) runs in 23 ms.
That's about 10 times faster. I would have expected D to be faster. Did
I do something wrong?
The first Lua version uses a simplified design. I thought maybe that is
unfair to ranges, which are more complicated. You could argue ranges
have more features and do more work. To make it fair, I made a second
Lua version of the above benchmark that emulates ranges. It is still 29
ms fast.
The full D version is here: http://pastebin.com/R5AGHyPx
The Lua version: http://pastebin.com/Sa7rp6uz
Lua version that emulates ranges: http://pastebin.com/eAKMSWyr
Could someone help me solving this mystery?
Or is D, unlike I thought, not suitable for high performance computing?
What should I do?
Without any imperical testing, I would guess this has something to do with
the lack of inlining for algorithmic functions. This is due primarily to
uses of enforce, which use lazy parameters, which are currently not
inlinable (also, ensure you use -O -release -inline for the most optimized
code).
I hope that someday this is solved, because it doesn't look very good for
D...
-Steve
