freedman@nas.nasa.gov (Richard S. Freedman) (06/13/91)
This is a summary of improvements to the CRAY unicos [6.0] sort that resulted from work done by a consultant at the Nasa Ames CCF. Since I received so many messages on this topic, I am posting this summary as a reply. The consultant said that the real problem is that unix sort was written for a machine with virtual memory, and since the cray does not have this feature the routine is very inefficient. Various people suggested that I use the SSD as the temporary disk storage cache, but this is not possible because our SSD is currently used as storage that mimics the scratch disk. The only improvements possible with a "quick fix" were: Assign the scratch disk as the temporary file space used by sort: [-T $TMP] recompile the sort routine so that it will use more memory when maximum memory is required [-y]. reset various parameters inside sort: increased number of scratch files to 50 set mthresh to 32 set treez to 128 set maximum memory to 2048 X 2048 More improvement is possible according to the consultant, but this will require time to implement the changes and more consultation with cray consultants. Richard Freedman NASA Ames freedman@amelia.nas.nasa.gov or freedman@pan.arc.nasa.gov