PARALLEL PROCESSING

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EXAMPLE

Calculate the column means of a data matrix

Divide data into equal groups (or blocks) of rows

for parallel processing (spawn)

Is the array in memory or does it need to be

read from disk?

Memory access is at least an order of

magnitude faster than disk access (depends on

whether the access is sequential or random)

Tuesday, August 20, 13

presentation - VirtualRDC @ Cornell - Cornell University

EXAMPLE Calculate the column means of a data matrix Divide data into equal groups (or blocks) of rows for parallel processing (spawn) Is the array in memory or does it need to be read from disk? Memory access is at least an order of magnitude faster than disk access (depends on whether the access is sequential or random) Tuesday, August 20, 13

EXAMPLE (CONTINUED) Within each group, calculate the sum for each column Store result (what if one core wants to write the result at the same time as another core?) Sum the results for each group and divide by the sample size Tuesday, August 20, 13

Page 1 and 2: Tuesday, August 20, 13 PARALLEL PRO
Page 3 and 4: THREADS VS PROCESSES Both can be us
Page 5 and 6: BENEFITS VS COSTS Using more cores
Page 7: AMDAHL’S LAW P=Number of Cores al
Page 11 and 12: SHOULD I GO PARALLEL? Careful tunin
Page 13 and 14: TAKE CONTROL OF IMPLICIT THREADS SA
Page 15 and 16: PBS PRO Job scheduler on the SSG th

PARALLEL PROCESSING

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