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CPU Load figuring

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I was just wondering what method RealTemp uses to calculate load on a CPU, and whether or not HyperThreading messes with the reading. I ask cause I have never on any machine seen the load match Task Manager.
 

unclewebb

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Hardly anyone has ever noticed this issue. When someone does notice, they assume that Microsoft must be right and RealTemp is wrong. Here is a quick test so you can come to your own conclusion.

I used the ThrottleStop TS Bench test which allows you to select how big a load you want to use. A Core i7-4700MQ is a hyper threaded 4 core CPU so it can process 8 threads at a time. I set the TS Bench to use 4 threads. In theory, this should create a load of 50%. It seems reasonable that the CPU will need to be active for another 0.5% to 1.0% so it can continue to process the Windows background tasks as this benchmark is running.



ThrottleStop shows the exact load on each thread. Add it all up and divide by 8 and it is showing a 50.9% load while RealTemp is showing a similar load of 50,5%. The slight difference is only because there is a slight difference in timing of these readings. On the other hand, the Task Manager is completely out to lunch. 72% is wrong.

I think the logic here is that Windows is basing its load value on this CPU having a default speed of 2400 MHz. Turbo Boost has this CPU running at a 34 multiplier not a 24 multiplier.

(34 / 24) - 1.4166

1.4166 X 50.5% = 71.5%

That is the only thing that makes some sort of sense to me but ultimately, 72% is wrong. Only half the CPU is being utilized during this test.

RealTemp and ThrottleStop use high performance timers within the CPU and follow a method recommended by Intel to determine the percentage of time the CPU is in the C0 state actively working on a task. The Windows 10 Task Manager graph is useless information but people still use this information to determine if they need a CPU with more cores.

Full Skylake support for RealTemp is on the things to do list. RealTemp 3.70 does not yet correctly support the new 6th Gen Skylake CPUs.
 
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Since I'm on Win 10 my CPU load is always 100%. Always, no matter I'm doing.

cpu_lod_crap.jpg


So even after all those years I still trust Kevin. :D
 

unclewebb

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You would figure with all the money hanging out of Microsoft's pockets that they could afford to hire a programmer or two and come up with a decent algorithm for their monitoring software.

Thanks burebista for your vote of confidence. :)
 
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Since my laptop (i3 2350M 2.3GHz) tends to overheat , i set max CPU state =77% in Windows 10 power settings . So , when i start chess , Real Temp shows 1.8GHz (77% of 2.3GHz) and load =100% . Task Manager shows the load to the max clock = 2.3GHz i.e. 77% , which is more accurate.

Anyway , Real Temp is a great tool because it warns of overheating
 
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So,

which one is telling the truth?


Real temp says my CPU is running at 3.8ghz


realtemp.PNG
 

CAPSLOCKSTUCK

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Apparently there is overclocking , bus speed from 133MHz to 185.5MHz and multiplier from 24 to 25 . Perhaps that time running at multiplier 20 . You know better

i cant work out if that is an answer, a question or a statement.


If you mean is it real time monitoring, yes it is, it is one snip. I then turned each one off to eliminate anomolies caused by running them together.
 

unclewebb

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...which one is telling the truth?

CPU-Z is used for MHz validation purposes so it is designed to report the maximum multiplier when lightly loaded. Both programs agree that your BCLK speed is 185.50 MHz. When lightly loaded, if RealTemp reports that your multiplier is less than what CPU-Z is reporting, that is usually because you have one of the C States enabled like C1E, C3 or C6. Disable all of your C States or put a load on your CPU and both programs will probably report the same multiplier. What RealTemp is showing you is a more accurate look at what your CPU multiplier is really doing internally. The X5670 uses a 25 multiplier but only when 1 or 2 cores are active. As more cores become active, the maximum multiplier automatically decreases. The number of active cores and the current multiplier can be changing hundreds of times a second and RealTemp does a great job tracking those changes. You can trust what it is telling you.

Real Temp shows 1.8GHz (77% of 2.3GHz) and load =100%

If RealTemp is showing that your CPU is running at 1.8 GHz then your CPU is running at 1.8 GHz. The BCLK stays the same. When adjusting the Max CPU State in Windows, your multiplier decreases so your CPU really is running slower.

The Load meter in RealTemp measures the percentage of time the CPU is in the C0 state which is the state a CPU is in when it is actively working on a task. As soon as a CPU has nothing to do, it will usually go into the low power C1 state. After that, depending on what C States you have enabled, it will drop down to the C1E, C3, C6 or C7 state and some of the new low power mobile Skylake CPUs also have C8, C9 and C10 that they can go into. RealTemp used to show C0% but not many people understood what it means when a CPU is in the C0 state so to keep things simple, I just called it Load instead.
 

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CPU-Z is used for MHz validation purposes so it is designed to report the maximum multiplier when lightly loaded. Both programs agree that your BCLK speed is 185.50 MHz. When lightly loaded, if RealTemp reports that your multiplier is less than what CPU-Z is reporting, that is usually because you have one of the C States enabled like C1E, C3 or C6. Disable all of your C States or put a load on your CPU and both programs will probably report the same multiplier. What RealTemp is showing you is a more accurate look at what your CPU multiplier is really doing internally. The X5670 uses a 25 multiplier but only when 1 or 2 cores are active. As more cores become active, the maximum multiplier automatically decreases. The number of active cores and the current multiplier can be changing hundreds of times a second and RealTemp does a great job tracking those changes. You can trust what it is telling you.


Thankyou for your succinct, intelligible answer......:toast:
 
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HI, i just installed real temp but it seems to only go up to 6 cores not 8 like my system has, is that just a limitation with the program?
 

unclewebb

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Unfortunately, RealTemp GT only supports 6 core CPUs.

You can give ThrottleStop a try to see if it can find all of your cores.

ThrottleStop 8.10 b2
https://www.sendspace.com/file/rnpe1c

It uses the same code as RealTemp but has better support for newer CPUs.

I do not have any access to systems with 6 or 8 core CPUs or dual CPUs so RealTemp development has been idle for a few years.
 
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Hardly anyone has ever noticed this issue. When someone does notice, they assume that Microsoft must be right and RealTemp is wrong. Here is a quick test so you can come to your own conclusion.

I used the ThrottleStop TS Bench test which allows you to select how big a load you want to use. A Core i7-4700MQ is a hyper threaded 4 core CPU so it can process 8 threads at a time. I set the TS Bench to use 4 threads. In theory, this should create a load of 50%. It seems reasonable that the CPU will need to be active for another 0.5% to 1.0% so it can continue to process the Windows background tasks as this benchmark is running.



ThrottleStop shows the exact load on each thread. Add it all up and divide by 8 and it is showing a 50.9% load while RealTemp is showing a similar load of 50,5%. The slight difference is only because there is a slight difference in timing of these readings. On the other hand, the Task Manager is completely out to lunch. 72% is wrong.

I think the logic here is that Windows is basing its load value on this CPU having a default speed of 2400 MHz. Turbo Boost has this CPU running at a 34 multiplier not a 24 multiplier.

(34 / 24) - 1.4166

1.4166 X 50.5% = 71.5%

That is the only thing that makes some sort of sense to me but ultimately, 72% is wrong. Only half the CPU is being utilized during this test.

RealTemp and ThrottleStop use high performance timers within the CPU and follow a method recommended by Intel to determine the percentage of time the CPU is in the C0 state actively working on a task. The Windows 10 Task Manager graph is useless information but people still use this information to determine if they need a CPU with more cores.

Full Skylake support for RealTemp is on the things to do list. RealTemp 3.70 does not yet correctly support the new 6th Gen Skylake CPUs.

Hmm I see RealTemp 4.00 in this screenshot, should I use this newer version for my skylake CPU?
If so, @unclewebb where can I download it? Thanks!
 
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unclewebb

ThrottleStop & RealTemp Author
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RealTemp 4.00 has not been released yet. I finally bought a Skylake CPU so now I can get back to finishing this project. More projects than time so it might be a while before it is ready for release.
 
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