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Symptom(s):
When running the VTune™ Performance Analyzer on an Itanium® 2-based system after upgrading to Microsoft* Windows Server* 2003 Service Pack 1 (SP1), you may see a dramatic decrease in the number of CPU_CYCLES events collected during an activity.
Cause:
Build 1289 of Microsoft Windows Server 2003 SP1 turned on CPU c-state in the operating system so that when the processor is not busy, it puts the processor into CPU sleep mode (c-state). This can be observed using PerfMon by monitoring C-state transitions.
This is not necessarily a bad thing and you may only want to reconfigure the operating system if you are comparing new sampling results with past sampling results that contain CPU_CYCLES samples in the system idle process.
Solution:
Look in the following registry key and set the following value to 0:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Power]
"IdleFrom0Delay"=dword:0
Then, reboot the system. Now, when you run an activity, if the system is idle, samples will be collected in the idle process.
Operating System:
| Windows Server* 2003, Windows Server* 2003 Standard Edition |
This applies to:
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