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GeneralRe: Execute driver help Pin
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QuestionI figured out how to stop my system from racing! Pin
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AnswerRe: I figured out how to stop my system from racing! Pin
CDP18024-Jun-12 19:35
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AnswerRe: I figured out how to stop my system from racing! Pin
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QuestionUnderstanding CPU performance measurements Pin
CDP180229-May-12 1:55
memberCDP180229-May-12 1:55 
I have been measuring the performance of a multithreaded application and, among other things, have made profiles of memory usage or thread synchronization. I also monitired the load on the CPU cores to get an impression of how well the threads are balanced.

My CPU is an I7 2600k and in the beginning everything looks really nice: The even cores show a load of 5 - 10%, with an occasional spike no larger than 30% when some event is being processed (= I clicked something). The odd numbered cores remain at 0%, so hyperthreading is not used. Then, without any obvious cause, core 0 (where obviously the more damanding threads are running) jumps to 100% and stays there. Looking at the profiles, the behavior of the main thread has changed. It now does not sleep to synchronize with the GPU anymore. It obviously now gets its job done just in time.

First I thought that the program may go crazy at times, but the profiles revealed no such thing. Testing on other machines that this does not happen on a notebook with an i5 processor, but reappears when tested on another i7 machine.

I have noticed a correlation with the CPU core's temperature and suspect that I am seeing some CPU temperature management in action. If the program does not create any unusual CPU load, then CPU 0 must have been clocked down. That would make sense to keep the core's temperature from rising and to draw less power. Something like the reverse of the famous i7 turbo boost. I could live with that if the performance of the application would not suffer from this feature. It appears as if that thing (if it exists) is a bit too eager to save power and starves the application's major threads.

Now, am I looking in the right direction? And what can be done to get a more favorable performance?
At least artificial intelligence already is superior to natural stupidity



modified 29-May-12 8:07am.

GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 5:30
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 6:52
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GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 7:07
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 7:55
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GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 8:30
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 9:18
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GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 9:37
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 10:27
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GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 10:34
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 11:06
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GeneralRe: Understanding CPU performance measurements Pin
harold aptroot29-May-12 11:13
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GeneralRe: Understanding CPU performance measurements Pin
CDP180229-May-12 11:17
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QuestionError opening a serial modem Pin
Member 800297324-May-12 6:53
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Peter_in_278024-May-12 16:18
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GeneralRe: Error opening a serial modem Pin
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GeneralRe: Error opening a serial modem Pin
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