SGI MIPS

Status

Cactus runs on SGI machines using IRIX (6.2, 6.3, 6.4, 6.5), and can be compiled using either 32 or 64 bits.

Notes

1. By default a 64 bit version of Cactus will be created, to produce a 32 bit version, configure with the option

   IRIX_BITS=32

2. SGI provide a native MPI implementation. This implementation is incompatible with using PTHREADS (which should be used with the CactusConnect/HTTPD thorn), and in this case for example MPICH should be used instead.

User Experiences

1. Malcolm Tobias (May 29 2002)

   Someone at NASA was looking into the performance of Cactus + MAHC on SGI systems, and noticed a significant speed-up by using larger page sizes. The default page size is 16kB, but one can use larger page sizes (for instance 1MB) with the command: dplace -data_pagesize 1m -stack_pagesize 1m cactus_benchTOV benchTOV.par

   Note that the system has to be configured to allow larger pages sizes. You can check this with the command: `systune | grep percent_totalmem` to see whether any memory has been allocated for the various page sizes.

   I did some tests, and 1MB pages sizes seem pretty optimal. While the ADM system doesn't show much in the way of improvement (3.7% speed-up for BenchADM) I'm seeing about a 21% speedup for GRHydro. Perhaps this is due to the increased number of variables when evolving spacetime + hydro.

   One other warning, the code does appear to use more memory when using larger page sizes