SMP Tuning

The following table describes symmetric multiprocessing (SMP) tuning parameters and their settings.

Parameter	Settings	Impact
Control number of active IIS threads.	Monitor the Processor Queue Depth object under System in Windows NT Performance Monitor to see if you have too many threads active. If you have N processors in your system, a queue depth between N and 3N is good. Leave values at the default if you are not sure. For static workloads, you can set MaxPoolThreads to 1 and PoolThreadLimit to the number of processors in your system. (These values are set in the Windows NT registry using Regedt32.exe. See the following topics for details on setting these parameters.)	There should be enough threads in the system so that incoming requests don't get blocked. However, each thread uses system resources and can potentially cause unnecessary context switches. The goal is to maximize the number of threads IIS uses without causing excess context switches. Doing so will ensure better performance on SMP hardware.

Parameter

Settings

Impact

Control number of active IIS threads.

Monitor the Processor Queue Depth object under System in Windows NT Performance Monitor to see if you have too many threads active.

If you have N processors in your system, a queue depth between N and 3N is good. Leave values at the default if you are not sure.

For static workloads, you can set MaxPoolThreads to 1 and PoolThreadLimit to the number of processors in your system. (These values are set in the Windows NT registry using Regedt32.exe. See the following topics for details on setting these parameters.)

There should be enough threads in the system so that incoming requests don't get blocked. However, each thread uses system resources and can potentially cause unnecessary context switches. The goal is to maximize the number of threads IIS uses without causing excess context switches. Doing so will ensure better performance on SMP hardware.