this out is by counting instructions and dividing by CPU speed. If there is a large discrepancy, you
Example 16-3 False Sharing
int a[128];
public class FalseSharing {
int index;
public void run() {
while (MANY_INTERATIONS)
a[index]++;
}
...
for (i = 0; i < 8 ;i++)
new FalseSharing(i * SEPARATION).start();
...
}
Summary
There are numerous machine designs, most of which will not affect our programming decisions.
There are a lot of issues concerning memory coherency, all of which are solved by using proper
locking. For very high performance programs, clever, semiportable cache blocking schemes and
data organization can have an enormous impact.
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