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System Idle Processthe "Idle" process. I record the elapsed time, wait 1 second and then record the new elapsed time. The result I get is: before: 175437046.875 after: 175438093.75 CPU time used: 1046.875 However I was running Prime95 at the same time and I obtained the following stats during the same interval (used managed .NET call Process.TotalProcessorTime.TotalMilliseconds): before: 295905.4912 after: 296896.9168 CPU time used: 991.4256 Now my understanding of the System Idle Process is that it counts the spare CPU time only. However for a 1 second interval both the Idle and Prime95 processes appear to have clocked up nearly 1 second each! I must be missing something here because this should be impossible, correct? Just to clarify, I have a single CPU which only displays a single CPU graph in Task Manager (hence isn't hyper-threaded or dual core). Grateful for any guidance, thanks! -- ______ ___ __ /_ __/_ __/ _ )_______ ___ _/ /_____ ____ / / / // / _ / __/ -_) _ `/ '_/ -_) __/ /_/ \_, /____/_/ \__/\_,_/_/\_\\__/_/ /___/ There are 10 types of people in this world; those who understand the binary numbering system and those who don't. There's no place like 127.0.0.1. ASCII a silly question, get a silly ANSI. You are using 2 different timings:
Idle process: Elapsed CPU time Prime95: TotalProcessorTime so you can not compare them ... TyBreaker wrote: Show quoteHide quote > I am using a performance counter to record the "Elapsed (CPU) time" of > the "Idle" process. I record the elapsed time, wait 1 second and then > record the new elapsed time. The result I get is: > > before: 175437046.875 > after: 175438093.75 > CPU time used: 1046.875 > > However I was running Prime95 at the same time and I obtained the > following stats during the same interval (used managed .NET call > Process.TotalProcessorTime.TotalMilliseconds): > > before: 295905.4912 > after: 296896.9168 > CPU time used: 991.4256 > > Now my understanding of the System Idle Process is that it counts the > spare CPU time only. However for a 1 second interval both the Idle and > Prime95 processes appear to have clocked up nearly 1 second each! I > must be missing something here because this should be impossible, > correct? Just to clarify, I have a single CPU which only displays a > single CPU graph in Task Manager (hence isn't hyper-threaded or dual core). > > Grateful for any guidance, thanks! > Theo Verweij wrote:
> You are using 2 different timings: Woah! Really? I though the total processor time meant the total > Idle process: Elapsed CPU time > Prime95: TotalProcessorTime > > so you can not compare them ... processor time (kernel time plus user time) for a particular process? -- ______ ___ __ /_ __/_ __/ _ )_______ ___ _/ /_____ ____ / / / // / _ / __/ -_) _ `/ '_/ -_) __/ /_/ \_, /____/_/ \__/\_,_/_/\_\\__/_/ /___/ There are 10 types of people in this world; those who understand the binary numbering system and those who don't. There's no place like 127.0.0.1. ASCII a silly question, get a silly ANSI. TyBreaker wrote:
> Theo Verweij wrote: The Visual Basic.NET help indicates Process.TotalProcessorTime is the >> You are using 2 different timings: >> Idle process: Elapsed CPU time >> Prime95: TotalProcessorTime >> >> so you can not compare them ... > > Woah! Really? I though the total processor time meant the total > processor time (kernel time plus user time) for a particular process? > total CPU time for the particular process. So I should be able to compare that to the Elapsed time for the System Idle Process over any given interval eg 1 second. Unless I'm missing something? -- ______ ___ __ /_ __/_ __/ _ )_______ ___ _/ /_____ ____ / / / // / _ / __/ -_) _ `/ '_/ -_) __/ /_/ \_, /____/_/ \__/\_,_/_/\_\\__/_/ /___/ There are 10 types of people in this world; those who understand the binary numbering system and those who don't. There's no place like 127.0.0.1. ASCII a silly question, get a silly ANSI. TotalProcessorTime: The processortime consumed by the process
ElapsedCpuTime: The cputime elapsed between 2 measurements, not neccesary used by your process (preemtive multitasking ...) TyBreaker wrote: Show quoteHide quote > TyBreaker wrote: >> Theo Verweij wrote: >>> You are using 2 different timings: >>> Idle process: Elapsed CPU time >>> Prime95: TotalProcessorTime >>> >>> so you can not compare them ... >> >> Woah! Really? I though the total processor time meant the total >> processor time (kernel time plus user time) for a particular process? >> > > The Visual Basic.NET help indicates Process.TotalProcessorTime is the > total CPU time for the particular process. So I should be able to > compare that to the Elapsed time for the System Idle Process over any > given interval eg 1 second. Unless I'm missing something? > To be more precise:
Prime95 is measuring the total processor time used by your process. Your process used 991.4 milliseconds The elapsedcputime is measuring the real processor time that has elapsed (1 second/second/processor, so with dual processor there are 2 cpu seconds per second). The time elapsed on your single processor machine was 1046.8 milliseconds. This means that 1046.8 - 991.4 = 55.4 milliseconds were used for one or more other processes. That the measurement of the elapsed cpu time isn't exactly 1 second is caused by the time slices of the preemtive multitasking, wich are variable and at least 20ms each. Theo Verweij wrote: Show quoteHide quote > TotalProcessorTime: The processortime consumed by the process > ElapsedCpuTime: The cputime elapsed between 2 measurements, not > neccesary used by your process (preemtive multitasking ...) > > TyBreaker wrote: >> TyBreaker wrote: >>> Theo Verweij wrote: >>>> You are using 2 different timings: >>>> Idle process: Elapsed CPU time >>>> Prime95: TotalProcessorTime >>>> >>>> so you can not compare them ... >>> >>> Woah! Really? I though the total processor time meant the total >>> processor time (kernel time plus user time) for a particular process? >>> >> >> The Visual Basic.NET help indicates Process.TotalProcessorTime is the >> total CPU time for the particular process. So I should be able to >> compare that to the Elapsed time for the System Idle Process over any >> given interval eg 1 second. Unless I'm missing something? >> Theo Verweij wrote:
> Prime95 is measuring the total processor time used by your process. OK, understood.> Your process used 991.4 milliseconds > The elapsedcputime is measuring the real processor time that has elapsed Ah this is where I'm confused then. I ran perfmon to see what counters > (1 second/second/processor, so with dual processor there are 2 cpu > seconds per second). The time elapsed on your single processor machine > was 1046.8 milliseconds. existed and the description for Process\Elapsed Time indicates it records "The total elapsed time, in seconds, that this process has been running." so I understood it to be specific to the particular process I had nominated - in this case the Idle process: Private IdleCpuUsage As PerformanceCounter = New PerformanceCounter("Process", "Elapsed Time", "Idle") I notice I do get different values for this performance counter depending on whether I point it at Idle or say, Firefox. If it is recording the total CPU time irrespective of any particular process, shouldn't the value being graphed be the same irrespective of which process I nominate? -- ______ ___ __ /_ __/_ __/ _ )_______ ___ _/ /_____ ____ / / / // / _ / __/ -_) _ `/ '_/ -_) __/ /_/ \_, /____/_/ \__/\_,_/_/\_\\__/_/ /___/ There are 10 types of people in this world; those who understand the binary numbering system and those who don't. There's no place like 127.0.0.1. ASCII a silly question, get a silly ANSI. 
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