“CPU Yields by Engine” reports the number of times each Adaptive Server engine yielded to the operating system. “% of total” data is the percentage of times an engine yielded as a percentage of the combined yields for all engines.
“Total CPU Yields” reports the combined data over all engines. However, an engine with one or more pending asynchronous disk IOs does not yield, even when runnable process search count is exhausted.
If the “Engine Busy Utilization” data indicates low engine utilization, use “CPU Yields by Engine” to determine whether the “Engine Busy Utilization” data reflects a truly inactive engine or one that is frequently starved out of the CPU by the operating system.
When an engine is not busy, it yields to the CPU after a period of time related to the runnable process search count parameter. A high value for “CPU Yields by Engine” indicates that the engine yielded voluntarily.
Engine Busy Low/CPU Yields Low – a higher value for the I/O Busy% column than for the CPU Busy% column indicates a large amount of pending I/O. Look for changes you can make at the operating system level to solve bottlenecks in I/O processing. If the Adaptive Server system CPU time is too high (based on operating system output), decrease the value for runnable process search count.
Engine Busy Low/CPU Yields High – engine is inactive.
Engine Busy High/CPU Yields Low – Adaptive Server is very busy and has jobs to run. Adding engines will probably help performance.
Engine Busy High/CPU Yields High – this should be the case when a normal number of user connections running simple queries. It is likely that lowering runnable process search count will have little or no effect. Adding engines is also unlikely to help, unless ‘Engine Busy Utilization” is very high.
For more information about configuration parameters, see Chapter 5, “Setting Configuration Parameters,” in the System Administration Guide, Volume 1.
CPU Yields by Engine per sec per xact count % of total ------------------------ ------------ ----------- -------- --------- Engine 0 73.5 1.8 44087 26.2 % Engine 1 40.4 1.0 24224 14.4 % Engine 2 23.7 0.6 14208 8.4 % Engine 3 36.2 0.9 21746 12.9 % Engine 4 38.7 1.0 23207 13.8 % Engine 5 41.3 1.0 24760 14.7 % Engine 6 26.8 0.7 16108 9.6 % ---------------------- ------------ ---------- -------- Total CPU Yields 280.6 6.9 168340
