5 ms·

Just took a quick peek at the binary-trees C code. Why using openmp while the others don't? why use recursive functions? The C implementation is not correctly o

by wuxb 6y ago

Just took a quick peek at the binary-trees C code. Why using openmp while the others don't? why use recursive functions? The C implementation is not correctly optimized. People just paid more attention to Rust and other languages. Rust can be as fast as C, but "faster" is really misleading. BTW, I use clang all the time since it's better than GCC.

Tade0 6y ago
It seems that someone simply tacked openmp on without checking if it actually increases performance in this case - which is unusual, because I remember a course in college, part of which was a project aiming to teach the student that openmp is not a silver bullet and should be used only when it actually helps.
- igouy 6y ago
  How do you know that this is not one of those cases when openmp actually helps?
- JZerf 6y ago
  I submitted the C binary-trees program. I did check to see if OpenMP increased the performance and it most certainly does. Just looking at the CPU and clock time usage on https://benchmarksgame-team.pages.debian.net/benchmarksgame/performance/binarytrees.html https://benchmarksgame-team.pages.debian.net/benchmarksgame/... you can see that the clock time used is about one third of the CPU time that was used.
JZerf 6y ago
You're probably referring to the C program I submitted. OpenMP is only available for C, C++, and Fortran so that is why most programs won't use it. However most of the other programming languages have their own ways for doing multi-threading and many of the programs for this benchmark do make use of them. The rules at https://benchmarksgame-team.pages.debian.net/benchmarksgame/description/binarytrees.html#binarytrees https://benchmarksgame-team.pages.debian.net/benchmarksgame/... request that submitters use the same algorithms as existing programs and I try to follow that rule. I believe all the binary-trees programs are using recursive functions so naturally I did the same to avoid breaking the rule about using different algorithms.

by wuxb 6y ago

Tade0 6y ago

It seems that someone simply tacked openmp on without checking if it actually increases performance in this case - which is unusual, because I remember a course in college, part of which was a project aiming to teach the student that openmp is not a silver bullet and should be used only when it actually helps.

igouy 6y ago
How do you know that this is not one of those cases when openmp actually helps?
JZerf 6y ago
I submitted the C binary-trees program. I did check to see if OpenMP increased the performance and it most certainly does. Just looking at the CPU and clock time usage on https://benchmarksgame-team.pages.debian.net/benchmarksgame/performance/binarytrees.html https://benchmarksgame-team.pages.debian.net/benchmarksgame/... you can see that the clock time used is about one third of the CPU time that was used.

JZerf 6y ago

You're probably referring to the C program I submitted. OpenMP is only available for C, C++, and Fortran so that is why most programs won't use it. However most of the other programming languages have their own ways for doing multi-threading and many of the programs for this benchmark do make use of them. The rules at https://benchmarksgame-team.pages.debian.net/benchmarksgame/description/binarytrees.html#binarytrees https://benchmarksgame-team.pages.debian.net/benchmarksgame/... request that submitters use the same algorithms as existing programs and I try to follow that rule. I believe all the binary-trees programs are using recursive functions so naturally I did the same to avoid breaking the rule about using different algorithms.