runnable process search count

runnable process search count specifies the number of times an engine loops while looking for a runnable task before relinquishing the CPU to the operating system.

Summary Information
Default value	2000 (default value of 3 for the Cluster Edition)
Range of values	0 – 2147483647
Status	Dynamic
Display level	Comprehensive
Required role	System administrator
Configuration group	SQL Server Administration

Note: runnable process search count functions only when you configure SAP ASE for process kernel mode; it is nonfunctional for threaded kernel mode. Use alter thread pool pool_name with idle timeout = n instead.

SAP ASE engines check the run queue for runnable tasks whenever a task completes or exceeds its allotted time on the engine. At times, there are no tasks in the run queues. An engine can either relinquish the CPU to the operating system or continue to check for a task to run. Setting runnable process search count higher causes the engine to loop more times, thus holding the CPU for a longer time. Setting the runnable process search count lower causes the engine to release the CPU sooner.

If your machine is a uniprocessor that depends on helper threads to perform I/O, you may see some performance benefit from setting runnable process search to perform network I/O, disk I/O, or other operating system tasks. If a client, such as a bulk-copy operation, is running on the same machine as a single CPU server that uses helper threads, you may need to allow both the server and the client access to the CPU.

Note: If you are having performance problems, try setting runnable process search count to 3.

For SAP ASEs running on uniprocessor machines that do not use helper threads, and for multiprocessor machines, the default value should provide good performance.

With a runnable process search count value of 3, the Cluster Edition can better share the system CPU with other processes running on the same machine. However, if you set runnable process search count to 3 and SAP ASE is running as a standalone process, users may experience delays in server response times. In this case, reset runnable process search count to 2000.

Use sp_sysmon to determine how the runnable process search count parameter affects the SAP ASE use of CPU cycles, engine yields to the operating system, and blocking network checks. See the Performance and Tuning Series: Monitoring SAP Adaptive Server with sp_sysmon.