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 |
runnable process search count functions
only when you configure Adaptive Server for process kernel mode;
it is nonfunctional for threaded kernel mode. Use alter
thread pool pool_name with idle timeout = n instead.
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.
Adaptive Server 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.
If you are having performance problems, try setting runnable
process search count to 3.
For Adaptive Servers 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 Adaptive Server 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 Adaptive Server use of CPU cycles, engine yields to the operating system, and blocking network checks. See the Performance and Tuning Series: Monitoring Adaptive Server with sp_sysmon.
runnable process search count and alter thread pool ...idle timeout both indicate how Adaptive Server looks for work:
runnable process search count specifies the number of loops Adaptive Server spends looking for work, and is a server-wide parameter.
alter thread pool ...idle timeout specifies the period of time Adaptive Server spends looking for work, and is tuned according to individual thread pools. idle timeout is more consistent across processors with varying speeds.
