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Whats the time interval used to calculate CPU utilization?


Ruuwa
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Greetings,

Would like to ask some questions regarding AIDA64's method of calculating the utilization value of a specific logic core in a multi core, HT enabled Intel Haswell processor. Especially about the time frame it considers. Let's assume I set an update frequency of 1 sec, so a new value will be logged/shown every second. Will it reflect the utilization based on the previous 100 ns / 100 ms / 1s? What is the time interval during which the algorithm counts system/idle time? Does it shows an averaged value of several utilization values calculated in the last 1 sec or just the last reported value?

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On ‎2017‎. ‎05‎. ‎14‎. at 7:01 PM, Ruuwa said:

Greetings,

Would like to ask some questions regarding AIDA64's method of calculating the utilization value of a specific logic core in a multi core, HT enabled Intel Haswell processor. Especially about the time frame it considers. Let's assume I set an update frequency of 1 sec, so a new value will be logged/shown every second. Will it reflect the utilization based on the previous 100 ns / 100 ms / 1s? What is the time interval during which the algorithm counts system/idle time? Does it shows an averaged value of several utilization values calculated in the last 1 sec or just the last reported value?

When you configure a 1 sec update rate, then the actual CPU utilization value will reflect the average CPU utilization over a 1 second period.

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Thank you, just one more thing. Is it the same if I set a shorter, eg 500 ms logging frequency, does it reflects the utilization of the last 500 ms even when the load and readout delay does not allow for a log entry to be produced every 500 ms? Or will it continue counting until the next readout whenever may it happen?

I guess it to be the latter from results like the one on the attached picture. The marked entries (between the magenta lines) are ~1 second away from each other, while the ones before are with about 0,5 sec. On top are the utilization values, then core frequencies, temperatures and power consumption at the bottom. Data all gathered by AIDA logging to CSV.

Is it safe to say, that because of the load by other applications, the logging gets delayed, the interval gets stretched? And it may also include some time spent on lower clock rates, because reaching TDP limits.

Thank you again for the help to interpret the collected utilization values correctly!

PS2_HCPUstats_start_enh.png

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Yes, it would be nice to have a slightly more granular utilization value, but only if the logging can keep up with the shorter intervals. I would not put it as a high priority issue, since knowing the interval to be 1 sec and independent of the preset logging frequency allows a good enough guess what happened. On a slightly other topic, can you add a sub second part to the logged time value? (HH:MM:SS,ss)? Just to see how frequently can the system produce a log entry when trying to log as frequently as possible.

 

Thank you for the answers!

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On ‎2017‎. ‎05‎. ‎22‎. at 1:03 PM, Ruuwa said:

On a slightly other topic, can you add a sub second part to the logged time value? (HH:MM:SS,ss)? Just to see how frequently can the system produce a log entry when trying to log as frequently as possible.

Thank you for the answers!

I don't think that's necessary, since you can easily estimate the update frequency by looking at the frequency of values.  So e.g. if you have 5 updates with the same HH:MM:SS value, then the actual update rate is 200 millisec.

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On 2017. 05. 22. at 1:03 PM, Ruuwa said:

Yes, it would be nice to have a slightly more granular utilization value, but only if the logging can keep up with the shorter intervals.

We'll decrease the minimum update rate to 0.1 sec (from the current 1 sec) in the next AIDA64 beta update that is rolling out later today.

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