slide 19 of 19

Code Optimizations

• Don't use shared objects when locals will do
• Minimize use of atomic locks
• Data layout to avoid "false sharing"
  • Even with shared L2 cache, have separate L1 caches
  • a and b are in the same c-unit cache line iff ((int) a) & ~(c - 1) == ((int) b) & ~(c - 1)
  • If a and b are >= c units apart, they must be in different lines
• Use volatile attribute only when reference requires

The next set of slides is available from http://yara.ecn.purdue.edu/~pplinux/ICPP96/