Specifications

April 2012 v1 AMD Opteron™ 6200 Linux Tuning Guide
17
3.3 Check Configuration After Installing Linux
Run free: at the command line and check that the total memory is the expected size, 65958808, in the
following example:
bash> free
total used free shared buffers cached
Mem: 65958808 5401568 60557240 0 151892 2483496
-/+ buffers/cache: 2766180 63192628
Swap: 2104472 0 2104472
If total memory is only showing about 3GB and you know you have installed more than that, then the most
likely cause is a kernel that does not fully support AMD Opteron™ 6200 Series processors.
It would also be useful to check the NUMA configuration; see 2.3 Check Numa Configuration for the details.
3.4 Compiler Choices
The AMD Opteron™ 4200/6200 Series processors include a variety of new instructions that optimize compute-
intensive software. This includes AVX, FMA4, and XOP instructions. More information about these instructions
can be found in the AMD64 Architecture Programmer’s Manual at
http://support.amd.com/us/Embedded_TechDocs/43479.pdf.
For best possible performance, your code must be compiled with a compiler that is enabled to use these
features in AMD Opteron™ 4200/6200 Series processors. This is particularly important for floating point codes.
The following chart gives you a list of compilers that offer optimized support for AMD Opteron™ 4200/6200
Series processors.
This table shows the compilers supported for this processor at the time this document was published. Be sure
to consult http://developer.amd.com/zones/hpc/Pages/default.aspx for the latest compiler information.
Compiler Status SSSE3
SSE4.1-.2
AVX
FMA4
XOP
Auto
Generates
Code
Comments
GCC 4.6.2
GCC 4.7
Available
4 4 4
GCC 4.4 is included in RHEL 6.0 distribution
and should be updated to GCC 4.6.2 or 4.7
for optimized support
Open64 4.5 Available
4 4 4
Provides incremental performance (~2%
SPECCPU) and functionality improvements
PGI 11.9 Available
4 4 4
PGI Unified Binary™ technology combines
into a single executable or object file code
optimized for multiple AMD and Intel pro-
cessors
• GCC (GNU Compiler Collection) - 4.6.2 (or 4.7 which is a bit faster). These versions can generate FMA4
and AVX instructions.
- http://gcc.gnu.org/
• X86 Open64 Compiler Suite (4.5.1 or later).
- http://developer.amd.com/tools/open64/Pages/default.aspx