How much contention is acceptable

For the best performance, you want to achieve the least possible amount of global lock contention, both real and false.

Global lock contention includes false contention, XES contention, and IRLM contention. Aim for total global lock contention of less than 5%. When the global lock contention is less than 5%, the individual breakdown of false contention, XES contention, and IRLM contention is not significant.

Use the following guidelines to monitor your global lock contention.

• If the global lock contention is less than 3%, no action is necessary.
• If the global lock contention is 3–5%, no immediate action is necessary, but you should monitor your system.
• If the global lock contention is greater than 5%, identify the greatest contributor among false contention, XES contention, and IRLM contention, and tune your system accordingly.
• Ignore individual intervals with very low locking rates but very high false contention. This situation is not significant, and it often occurs on systems that use a one-minute statistics interval.