# a bit lost - core i7 920 and cpufreqd

## albright

I have a core i7 920 and tried to turn on cpu scaling.

My results are a little perplexing.

When cpufreqd starts its sets the governor to powersave and

max freq on all cpus (there are 8 visible - 4 cores x 2) to

1600000. Adjusting /etc/cpufreqd.conf does not affect this

so far as I can tell.

But if I *manually* change the governor to ondemand and

set max freq to 2668000 then it *appears* to work

properly.

That is, under load cpuinfo reports that the cpu freq goes up

and falls back when not under load.

For example, if I run boinc on 4 cpus then I get this result:

```
system # cat /proc/cpuinfo | grep MH

cpu MHz         : 2668.000

cpu MHz         : 2668.000

cpu MHz         : 1600.000

cpu MHz         : 1600.000

cpu MHz         : 1600.000

cpu MHz         : 2668.000

cpu MHz         : 2668.000

cpu MHz         : 1600.000

```

I should also point out that the speeds are cycled through all

the cpus which I guess is a good thing.

So my question is first, is this really working or is it some artifact

of cpuinfo reporting? (can the i7 really change frequencies on

all 8 cpus given there are just 4 cores?)

and second, is there a way to get cpufreqd to set things up properly

automatically or do I have to run the setup script every bootup?

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## durian

Not really answering your question, but did you also see: https://forums.gentoo.org/viewtopic-t-801716-highlight-.html?

-peter

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## albright

Thanks very much for that link which I had not seen.

Turns out cpuinfo is lying.

The core i7 cannot independent clock each core - so if

boinc is running on even 1 thread all cores are running

at full speed. Since I run boinc all the time cpufreq is

pretty useless for me. 

But if the system is idle then it does downclock all

the cores.

edit: also worth mentioning that the turbo feature seems to be working

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## albright

sorry to self reply but I found out some things that

might be of interest

first, once I had the ondemand governor built in

the kernel cpufreqd set up everything properly

second, the turbo feature only seems to work if

cpufreqd service is running ....

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## Timbers2k

I far as I know, you don't need cpufreqd to get the turbo feature. You only need to have the kernel option. I have found that the best setting for my i7-920 is to set the governor to performance and let the CPU take care of itself. You won't see it in the display, but the CPU itself will throttle itself down when idle, and keep it just as cool as trying to control it with one of the other governors. It is also much faster switching then when using ondemand.

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## albright

 *Quote:*   

>   I far as I know, you don't need cpufreqd to get the turbo feature. You only need to have the kernel option

 

yes that works - thanks. I prefer not to run unnecessary services.

But I notice that I never get the 22x multiplier which the i7z program

suggests I should on occasion

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## Timbers2k

I haven't tried to verify that it does go to 22 on occasion, but it should. I guess you could keep the i7z program running while testing, but I never bothered. My system is so fast for everything I'm doing that I just don't care enough to work on it. Let us know what you find.

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## durian

I have been runing the i7z program a while, but I have never seen more than four times x21 in the list. 

Never really tried to tweak anything - as someone remarked earlier, that thing is FAST :)

-peter

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## albright

on an otherwise idle system I started a single instance

of burnP6 - but the multiplier went to 21 and never went

to 22 ...

same with superpi (BTW superpi 20 = 12.140 secs total for

one core; 20.150 for all 8 )

But I agree it doesn't matter very much. I'm not hurting

for speed. Just curious.

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