Parallel Computer Architecture

4.2 Evaluating a Real Machine 225

~

8

Γ

| Cold/capacity

[?1 True sharing

□ False sharing

8 16

128 256 8 16

Une size (bytes)

64 128 256

FIGURE 4.5 Impact of problem size and number of processors on the spatial locality behavior

of Radix sorting. The miss rate is broken down into cold/capacity misses, true sharing (inherent com-

munication) misses, and misses due to false sharing of data. As the block size increases for

a

given prob-

lem size and number of processors, there comes a point when the critical ratio discussed in the text

becomes smaller than a threshold multiple of block size, and substantial false sharing is experienced.

This threshol ...