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Excessive buffer busy waits

I have excessive buffer busy waits on a three-node clustered system... I've modified my freelists. It improved a little but not to my satisfaction. What's next?
Are you sure that buffer busy waits are negatively affecting performance? I'd suggest that you perform an extended trace of some typical application operations (using dbms_support), and analyze the formatted trace file to see just how much elapsed time buffer busy waits are consuming. If they do turn out to constitute a significant percentage of elapsed time, you'll have to diagnose the reasons that certain blocks have such a high degree of concurrent access, possibly leading to changes in your application. Of course, if you're unable to change the application, you may have to do what mitigation you can in the database alone. For example, if the contention is for index blocks, and the index is based on an ascending sequence, replacing the conventional index with a reverse-key index will distribute key values across more blocks, thus reducing contention.

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