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Oracle Performance Firefighting, written by
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* Increase CPU power. In most cases, the CPU subsystem will be heavily utilized and probably the operating system bottleneck. Latch acquisition and the associated memory management consume a tremendous about of CPU. Do anything you can think of to reduce CPU consumption and to increase CPU capacity. Look for processes that do not or should not be running during peak times. Consider adding CPUs or using faster CPUs. If you are running in a virtual environment, considering ensuring this Oracle system has increased CPU resources. However, be aware that unless the application workload has considerably increased, additional CPU power typically will be consumed rather quickly. The real solution probably lies elsewhere. Increasing CPU power may be a good quick fix, but it will probably not truly solve the problem.
* Check for cloning issues. Whenever I encounter CBC latch contention, I check to ensure cloning is not the issue. This is rarely the case, but if it is, the solution path (as outlined previously) is very different from all the other solutions.
* Increase CBC latches. This usually brings some relief, but not nearly as much as tuning the logical IO SQL. The hidden instance parameter _db_block_hash_latches controls the number of CBC latches. Before you change this, be aware there may be support issues from both Oracle and your application vendor.
©2009, 2010 by Craig Shallahamer. This is copyrighted material.
PleaseOut of respect for those involved in the creation of the book and also for
their familes, we ask you to respect the copyright both in intent and deed. Thank you.
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