set cache

set cache nbytes <nslots> <preemption>

nbytes       Size of the cache in bytes.
nslots       Number of chunk slots in the raw data chunk cache.
preemption   Size of the chunk in the Z dimension. Default value is 1.

Usage Notes

Cache size is set on a per-file basis.

The nbytes parameter is the total size of the raw data chunk cache for a particular file. In most cases increasing this number will improve performance, as long as you have enough free memory. Default value is 256 Mb.

The nslots parameter is the number of chunk slots in the raw data chunk cache for a particular file. Increasing this value reduces the number of cache collisions, but slightly increases the memory used. Due to the hashing strategy, this value should ideally be a prime number, and not an integer factor of the chunk size. As a rule of thumb, this value should be at least 10 times the number of chunks that can fit in rdcc_nbytes bytes, and should ideally be at least 100 times that number of chunks. Default value is 51203.

The preemption parameter guides the determination of which chunks are deleted from the cache when it becomes full. Default value is 0.75.

Current values of the cache parameters may be discovered with the 'query cache' command.

This command is available with GrADS version 2.0.a8 or later.

Examples