Anke Kamrath - CESM - UCAR
Anke Kamrath - CESM - UCAR
Anke Kamrath - CESM - UCAR
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Inefficient Use of Memory<br />
• Replicated Metadata<br />
– Describes the location of something else<br />
• eg: message passing schedule, domain decomposition<br />
– Consider: p i sends ‘n’ bytes to p j<br />
• Don’t store information about p j, p i on p k if k != i,j<br />
– High resolution version of CLM on 10K processors --> 29 TB<br />
– Ignorance is bliss! :-)<br />
• Excessive Global Arrays<br />
– global arrays: an array the size of the entire computational<br />
mesh<br />
– Persistent versus temporary global arrays<br />
– Low res ---> no big deal; High res --> can be fatal !<br />
– Example: CLM<br />
• Original: ~500<br />
• Now: 1 (temporary)<br />
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