Estimation of CPU Load and Power Consumption

[thn80]

Hello,

my current system uses an Core i5-4690S with a CPU Mark of 5501 to run some virtual machines. The system is running at 3.2 GHz with an overall CPU load (over all cores) of around 40%.

How could I estimate the CPU load and resulting power consumption if the same virtual machines are transferred to a system with another CPU?
I know that an exact value will not be possible, but I think a rough estimation could be done.

Current model:
Intel Core i5-4690S (4 Cores, 4 Threads, CPU Mark 5501)

For the new CPU let's take the following models:
Intel Xeon E-2378 (8 Cores, 16 Threads, CPU Mark 17215)
Intel Xeon W-1290 (10 Cores, 20 Threads, CPU Mark 20123)
Intel Xeon W-1290T (10 Cores, 20 Threads, CPU Mark 18409)
Intel Xeon D-1537 (8 Cores, 16 Threads, CPU Mark 7176)

Any ideas?
Could I simply use a mathematical rule of three with the CPU Marks to convert the load to a percentage of CPU load?
In case this is fine, how could the percentage of load of a CPU be converted to the consumed power in Watts?
Are there any (online-)tools doing such a conversion?

Thanks a lot for your help,

Thomas

 

[hmw]

If you're comparing server/workstation class CPUs to consumer CPUs - you need to keep in mind that workstation/server mainboards and CPUs will idle far less or enter C & P states less often leading to higher performance at the cost of higher power consumption

The other is that even lower end server class CPUs pack 2x ~ 4x more L2/L3 cache and that makes a LOT of difference when running VMs

 

[thn80]

Thanks for the information, especially about the C & P states and the L2/L3 cache.
Nevertheless, can we come to a rough number for the power consumption on those CPUs?

 

[unwind-protect]

It is super hard to pre-calculate or estimate the power consumption of a partially loaded CPU. There is a lot of machinery on the chip that gets put into powersaving mode when fully or mostly idle, but how much of it is woken up for partial load is anyone's guess.

 

[hmw]

The only figures for the i5-4690K (not S) are almost a decade old and are around 48W idle to 110W at full load for power measured at the wall. STH has an article on the 2378G where they mention a 121W total system draw and 28W idle. I have a E-2126G that idles at 20W with IPMI and 10G NICs in ProxMox and rarely goes beyond 60W average

You cannot use PassMark /CPU Mark to infer power consumption, it simply doesn't work that way. And this is without taking into consideration modern CPUs which can enter deep idle states when waiting for I/O. So even if you have many processes running, the CPU will appear to consume 20W ~ 50W instead of the full 85W

Another thing: when comparing Xeon E-23XX vs Xeon W-XXX you're comparing apples and oranges. The E-23XX Xeons will stay within their TDP limits, which is very rare for an Intel processor.

The Xeon W have the more typical Intel behavior the TDP figure being a sort of 'yeah that is average consumption and peak is much higher' - the 125W Xeon W will happily consume 180W at peak load

Forget CPU Mark and design for the total power consumption of your specific motherboard + cpu and add-on cards

 

[thn80]

Another thing: when comparing Xeon E-23XX vs Xeon W-XXX you're comparing apples and oranges. The E-23XX Xeons will stay within their TDP limits, which is very rare for an Intel processor.

The Xeon W have the more typical Intel behavior the TDP figure being a sort of 'yeah that is average consumption and peak is much higher' - the 125W Xeon W will happily consume 180W at peak load

Thanks for your very detailled comment. Could you just make the point about the Xeons a bit more detailled, please? Why will the Xeons stay inside their TDP limits?

 

[hmw]

Thanks for your very detailled comment. Could you just make the point about the Xeons a bit more detailled, please? Why will the Xeons stay inside their TDP limits?

That's just how Intel designed the Xeon E-21xx/E-22xx/E-23xx series. They're meant to be used at the edge and hence just keep inside the TDP envelope.

In contrast the Xeon W-XXX series are workstation class CPUs. Intel designed them with performance in mind hence they will sustain high clocks as long as there's adequate cooling

As long as you have a motherboard that allows you to set PL1 and PL2 parameters, you can take even Xeon W (or pretty much any Intel) processors and confine them to a power envelope. If you have Dell or Supermicro servers you can actually confine the entire system to a specific power envelope