# Kernel options for later Intel CPU's [SOLVED]

## Tony0945

I'm running AMD k8 & K10 but considering Intel (to save power). I noticed that the kernel has only these two options:

Intel P4/Netburst (netburst?)  Optimize for Intel Pentium 4, Pentium D and older Nocona/Dempsey                                                                                                                     │  

  │ Xeon CPUs with Intel 64bit which is compatible with x86-64.                                                                                                                          │  

  │ Note that the latest Xeons (Xeon 51xx and 53xx) are not based on the                                                                                                                 │  

  │ Netburst core and shouldn't use this option. You can distinguish them                                                                                                                │  

  │ using the cpu family field                                                                                                                                                           │  

  │ in /proc/cpuinfo. Family 15 is an older Xeon, Family 6 a newer one.        

And:

Core2/ Newer Xeon                                                                                                                                                                                       │  

  │ Select this for Intel Core 2 and newer Core 2 Xeons (Xeon 51xx and                                                                                                                   │  

  │ 53xx) CPUs. You can distinguish newer from older Xeons by the CPU                                                                                                                    │  

  │ family in /proc/cpuinfo. Newer ones have 6 and older ones 15                                                                                                                         │  

  │ (not a typo) 

This stuff sounds ancient. What about non-Xeon's? Haswell, Devil's canyon, Skylake?  I've seen Xeons in industrial equipment but everyone else I know has a non-Xeon.

Should I stick with AMD for a pure Gentoo system despite their throwing heat like a blowtorch?  Or are experimental options to use later features in the works?Last edited by Tony0945 on Fri Jan 15, 2016 8:56 pm; edited 1 time in total

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## NeddySeagoon

Tony0945,

There is a patch, a patch set even.  emerge gentoo-sources with the experimental USE flag.

I've not kept up with what that gives you, so you need to do some reading.

As usual, if it breaks, you can keep all the pieces.

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## geki

Just wondering.

Do you want to save power and therefore enable power saving options?

Or do you want to change the march flag for gcc?

The selection you mention does not save power, neither would a patch for other cpus to that selection.

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## Tony0945

Thanks Neddy!  

Geki:  The Intel high performance CPU's take 91 watts, the AMD 220 watts. I have enough problems with ComEd complaining that my electricity usage is too high.  Yes, I use the cpufreq module (I forget the name), it cuts my present CPU's power from 125W to 60 watts at idle at quarter speed.

What I'd really like is something like my old k6-3+ system that takes 40W TOTAL, but I realize that's impossible, especially since I have three hard drives.

I don't actually have an Intel system yet, I'm exploring options.

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## Tony0945

 *NeddySeagoon wrote:*   

> Tony0945,
> 
> There is a patch, a patch set even.  emerge gentoo-sources with the experimental USE flag.
> 
> I've not kept up with what that gives you, so you need to do some reading.
> ...

 

I set the flag and not only does it give many more intel options including Core i7, but it now shows a separate option for K-10/Athlon II/Phenom II, which I am in the process of compiling now.

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## geki

My Intel i5 4-core system has 45W TDP (MAX power). The Intel T-series have low power consumption. IIRC, U-series was even lower, I may be wrong.

Though, are not the fastest ones. However your needs are. Mine is power consumption.

```
$ uname -a

Linux ana 4.3.3-gentoo #1 SMP PREEMPT Mon Dec 28 01:36:37 CET 2015 x86_64 Intel(R) Core(TM) i5-2500T CPU @ 2.30GHz GenuineIntel GNU/Linux
```

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## toralf

Did you tried the ondemand governor of the kernel ? Works fine here (at Intel processors) since years.

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## Syl20

 *Tony0945 wrote:*   

> Core2/ Newer Xeon                                                                                                                                                                                       │  
> 
>   │ Select this for Intel Core 2 and newer Core 2 Xeons (Xeon 51xx and                                                                                                                   │  
> 
>   │ 53xx) CPUs. You can distinguish newer from older Xeons by the CPU                                                                                                                    │  
> ...

 

With this option, the kernel works well with all the Core2 and later Intel CPUs I own, including a Haswell one. Maybe experimental options provide better optimizations, but I didn't feel needing them yet. One day, I'll try...

The ondemand governor does the job.

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## chithanh

Nowadays for modern Intel CPUs it is mostly recommended to stay with the performance governor, and delegete power management to the intel_pstate driver instead.

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## 1clue

I have a communications-oriented 8-core Atom c2758 that advertises 20w tdp, and while it's not nearly as fast at compilation as an old i7 920 it's actually faster at compression and a few other things.  Not sure what it actually uses since I don't have a power meter.

I use core2 and the experimental flags, can't remember exactly what.  Works fine.  Use march=native.

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## Buffoon

```

 │                                                                                                          

 │                                 AMD Opteron/Athlon64/Hammer/K8                      

 │                                 AMD Opteron/Athlon64/Hammer/K8 with SSE3       

 │                                 AMD 61xx/7x50/PhenomX3/X4/II/K10                   

 │                                 AMD Barcelona                                                    

 │                                 AMD Bobcat                                                        

 │                                 AMD Bulldozer                                                     

 │                                 AMD Piledriver                                                      

 │                                 AMD Jaguar                                                          

 │                                 Intel P4 / older Netburst based Xeon                

 │                                 Intel Atom                                                

 │                                 Intel Core 2                                                   

 │                                 Intel Nehalem                                           

 │                                 Intel Westmere                                               

 │                                 Intel Silvermont                                                 

 │                                 Intel Sandy Bridge                                   

 │                                 Intel Ivy Bridge                                         

 │                                 Intel Haswell                                                 

 │                                 Intel Broadwell                                                     

 │                                 Generic-x86-64                                                 

 │                             <X> Native optimizations autodetected by GCC  

 
```

^^ This is what I use with my i3 6100 instead of setting CPU type.

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## Syl20

 *chithanh wrote:*   

> Nowadays for modern Intel CPUs it is mostly recommended to stay with the performance governor, and delegete power management to the intel_pstate driver instead.

 

Good to know, thank you.

Unfortunately, my laptop is too old, but some of my desktop machines can use intel_pstate. So, let's go...

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## wrc1944

When you use the experimental gentoo-sources USE flag, among other things at the end of processor section there is a "native" option, which lets GCC detect and utilize the features your hardware (CPU) is capable of.

It's better to use native than select a specific processor option in most cases, as your current gcc compiler version knows best.  After all, it is in charge of using your hardware to compile your binaries.   :Cool: 

I would also recommend that one use -march=native in your /etc/make.conf file.

I've been doing this for years now with absolutely no problems.

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