OCaml 微基准测试
我正在尝试对 c 和 ocaml 进行基本的微基准比较。我听说对于斐波那契程序，c 和 ocaml 大致相同，但我无法复制这些结果。我使用 gcc -O3 fib.c -o c-code 编译 c 代码，并使用 ocamlopt -o ocaml-code fibo.ml 编译 OCaml 代码。我使用 time ./c-code 和 time ./ocaml-code 进行计时。每次我执行此操作时，OCaml 都会花费 0.10 秒，而 c 代码每次大约需要 0.03 秒。除了这是一个简单的基准测试之外，还有没有办法让 ocaml 更快？谁能看到他们计算机上的时间吗？
奥卡米尔
#include <stdio.h>
int fibonacci(int n)
{
return n<3 ? 1 : fibonacci(n-1) + fibonacci(n-2);
}
int main(void)
{
printf("%d", fibonacci(34));
return 0;
}
let rec fibonacci n = if n < 3 then 1 else fibonacci(n-1) + fibonacci(n-2);;
print_int(fibonacci 34);;
I am trying a basic microbenchmark comparison of c with ocaml. I have heard that for the fibonacci program, c and ocaml are about the same, but I can't replicate those results. I compile the c code with gcc -O3 fib.c -o c-code, and compile the OCaml code with ocamlopt -o ocaml-code fibo.ml. I am timing by using time ./c-code and time ./ocaml-code. Every time I do this OCaml takes 0.10 seconds whereas the c code is about .03 seconds each time. Besides the fact that this is a naive benchmark, is there a way to make ocaml faster? Can anyone see what the times on their computers are?
C
#include <stdio.h>
int fibonacci(int n)
{
return n<3 ? 1 : fibonacci(n-1) + fibonacci(n-2);
}
int main(void)
{
printf("%d", fibonacci(34));
return 0;
}
OCaml
let rec fibonacci n = if n < 3 then 1 else fibonacci(n-1) + fibonacci(n-2);;
print_int(fibonacci 34);;
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当使用 gcc -O2 编译时，ML 版本已经击败了 C 版本，我认为这是一个相当不错的工作。查看 gcc -O3 生成的程序集，看起来 gcc 正在执行一些积极的内联和循环展开。为了使代码更快，我认为您必须重写代码，但您应该专注于更高级别的抽象。
The ML version already beats the C version when compiled with
gcc -O2, which I think is a pretty decent job. Looking at the assembly generated bygcc -O3, it looks likegccis doing some aggressive inlining and loop unrolling. To make the code faster, I think you would have to rewrite the code, but you should focus on higher level abstraction instead.我认为这只是 ocaml 的开销，与更大的程序相比会更有意义。
您可以使用
-S选项生成汇编输出，并使用-verbose来查看 ocaml 如何调用外部应用程序 (gcc)。此外，使用-p选项并通过gprof运行应用程序将有助于确定这是否是ocaml的开销，或者您实际上可以做的事情提升。干杯。
对于我的计算机，我得到以下信息，
I think this is just an overhead to ocaml, it would be more relevant to compare with a larger program.
You can use the
-Soption to produce assembly output, along with-verboseto see how ocaml calls external applications (gcc). Additionally, using the-poption and running your application throughgprofwill help determine if this is an overhead fromocaml, or something you can actually improve.Cheers.
For my computer I get the following,