Is there any compatibility considerations about mixed opteron and xeon cluster? I mean if I compile my source code in opteron 64 bit (using gcc), will the binary work on xeon?

Don't see why not, we compile firmware on all different Optiplex machines and they sport both AMD and Intel processors.

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

Whether or not the binary runs depends on what you use in your CFLAGS and CXXFLAGS. The thing you don't want to do is have a binary compiled with SIMD extensions that one of the chips cannot execute. For example, using "-msse4a" or "-march=barcelona" in your flags may lead to the Xeons segfaulting on an "illegal instruction" error as no Intel CPU supports all of the SSE4A instructions. Likewise, no current Opteron can run all of the instructions in Intel's SSSE3, SSE4.1, SSE4.2, or AVX instruction sets, so any flag that calls them (including the "-march" flags for Core 2 and Core i7 CPUs) may cause segfaults on AMD CPUs. If in doubt, don't set the -march and don't use any -msse* flags. You can use -msse3 if you are running dual-core or greater Opterons since all 64-bit Xeons and dual-core or later Opterons support SSE3. Past SSE3, the SIMD instructions AMD and Intel CPUs support vary. AMD is supposed to be adding support for most of Intel's SIMD instructions in Bulldozer, but that's not shipped yet.

-------------------------

Yeah, that's the great and terrible thing about optimizing compilers. There's often a legion of compiler flags that can be used with them some of those are quite useful for tuning an application. However, there are others that when used in the wrong context can cause problems that make you want to burst into tears and curl up into a ball on the floor.

Aside from problems like that... I don't expect there to be a lot of trouble. Depending on the software you use for clustering you might even be able to use mixed instruction sets... although that does increase the likelihood of weirdness by a bit.

-------------------------
Containment Breach

Do not meddle in the affairs of archers, for they are subtle and quick to anger.

Thanks, it was quite complete. I understand in what situations it might not work

I understand that compiling on opteron running on xeon is ok. But will compiling on xeon and running on opteron give the same performance as compiling/running on opteron?

-------------------------
sfw0140

Performance of compiled code on difference processors depends on what optimization flags are given to the compiler at compile time. Compiling on one CPU and running on another makes NO difference in performance, as long as the compiler optimization flags are not set to auto-detect and auto-optimize for the compiling CPU. So avoid using something like "-march=native" with GCC that will auto-optimize for the CPU the compilation is being performed on. In fact, if you are running on both Xeon and Opteron, don't do any processor-specific (-march) options.

-------------------------