How to calculate SPEED setting?

[support]

Hello,

We currently have configured our servers to use 100% of 1 CPU core. (So "SPEED" is set for "100%".)

We want to switch to the "Ghz" setting for SPEED so that we can better control cpu usage across all our servers, regardless of the servers CPU type and its speed.

We need to find a starting point for the Ghz value, and Im having difficulty understanding what is the equivalent value for our current setting.

So lets say that we have a Intel Xeon E3-1230 V2 @ 3.30GHz (8 processors reported in WHM/cpanel server info page). What is the SPEED (Ghz) that we should set which would be the same as 100%?

Thanks.

[sales]

From what I read the ncpu number doesn actually do anything anymore. So in your case if you set it to 100% they are using 3.3GHz

[henri]

> From what I read the ncpu number doesnt actually do anything anymore. So in your case if you set it to 100% they are using 3.3GHz

I dont think you are correct. The "ncpu" no longer does anything, but from what I can understand... if the new "speed" value is using percentage (%) then it will that value for one core. Heres a link to the documentation on the SPEED setting.

So in my example above, if I have set a value to SPEED of 100%, then it mean the users cpu LVE is limited to 100% of 1 core. (In my particular example, 100% divided by 8 cores means the users LVE is allowed 12.5% of total cpu power.)

What I dont understand is how this translates to Ghz. How I think it works is that since there are 8 cores, it would be 3.3ghz divided by 8 which is .4125Ghz per LVE.

This is what I am trying to understand, and it would be nice if Igor could chime in here to clarify if this "Ghz" calculation is correct.

Thanks!

[iseletsk]

If you want to set it in hz, just use exactly that parameter, like 1ghz. It would set the limit to whatever it is (as a fraction of a core) depending on the speed of your CPU.

[henri]

Hi Igor,

So lets say that we have a Intel Xeon E3-1230 V2 @ 3.30GHz (8 processors reported in WHM/cpanel server info page). What is the SPEED (Ghz) that we should set which would be the same as 100%?

[iseletsk]

3.30GHz

[bepari.payoneer]

Yes your explanation is exactly correct according to cloudlinux documentation.

[ckh]

Is the speed based on one physical core or one hyperthreaded core if the cpu has hyperthreading.

An E3-1220 has 4 cores and no hyperthreading.

cat /proc/cpuinfo reports:

4 Processors: Intel(R) Xeon(R) CPU E3-1220 v3 @ 3.10GHz
So 3.10 GHz would be one phyical core.

While an E3-1270, which as 4 physical cores and hyperthreading reports:

8 processors: Intel(R) Xeon(R) CPU E3-1270 v3 @ 3.50GHz

so is 3.50Ghz one physical core or one hyperthreaded core ( one half of a physical core ) ??

[chris.drayton]

> Is the speed based on one physical core or one hyperthreaded core if the cpu has hyperthreading.[br][br]An E3-1220 has 4 cores and no hyperthreading.[br][br]cat /proc/cpuinfo reports:[br][br]4 Processors: Intel(R) Xeon(R) CPU E3-1220 v3 @ 3.10GHz[br]So 3.10 GHz would be one phyical core.[br][br]While an E3-1270, which as 4 physical cores and hyperthreading reports:[br][br]8 processors: Intel(R) Xeon(R) CPU E3-1270 v3 @ 3.50GHz[br][br]so is 3.50Ghz one physical core or one hyperthreaded core ( one half of a physical core ) ??

This is an important question. Is the setting based on physical or logical cores? The OS will report 8 logical cores, so do we have 800% to play with - or is this based on only physical cores - 400%? Ive not found this documented anywhere, yet it would seem to be a fundamental question. Many people could be potentially offering more cpu but restricting their servers to half the available capacity. This needs to be clarified in the documentation.

[vmarchuk]

Hello,

SPEED limit considers logical cores. So if you have E3-1270 with hyperthreading enabled, you will have 8 logical cores and maximum SPEED = 800% as a result.