Linux Format forums

heiowge · Posted: Sat Sep 29, 2012 2:21 pm Post subject: what the...

Why is 1 core at full speed, but the rest are only at 800mhz? Is it that one only is being used, or that the rest have a fault?
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nelz · Posted: Sat Sep 29, 2012 6:08 pm Post subject:

It's probably the kernel scheduler reducing the speed until it's needed. If your kernel uses the on-demand governor, this is to be expected.
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heiowge · Posted: Sat Sep 29, 2012 6:17 pm Post subject:

Thanks nelz. Any idea if Mint 13 includes this?
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AMD PHENOM II X6, 14 GB DDR3, 500 GB hd, 1GB nVidia card, running Linux Mint 14 KDE / Win 7. Damn thing keeps breaking.

eeepc 1015PX, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd running Mint 14 MATE. Running great.

nelz · Posted: Sun Sep 30, 2012 11:11 am Post subject:

heiowge · Posted: Sun Sep 30, 2012 3:41 pm Post subject:

Paradigm Shifter · Joined: Sat May 19, 2012 1:16 pm Posts: 84

It's called Cool 'n' Quiet, the AMD equivalent to Intel Speedstep.

It's BIOS controlled, and in my experience great if you want to decrease idle power draw, but a nightmare if you've got any software that is reliant on CPU clock to control its internal timing count - Unreal Tournament engine games spring to mind here; if you install them with the CPU 'idle' they'll run in fast-forward due to the CPU clocking up to full speed when the game actually runs.

Run linpack or something similar, and you'll see all cores at their rated 3200MHz. Smile

It's interesting to see the evolution of power saving tech for CPUs - initially it was a bit of a sledgehammer solution (all cores clocked up or down) then it evolved to a load-based scenario (all cores have independent clock states depending on load) and the latest and greatest versions (semi-)intelligently work out how much a core can be overclocked based on load, TDP and temperature.

So, no, there's no fault there. It's doing what it's designed to. If you want it running full speed all the time, disable Cool 'n' Quiet in the BIOS. Smile

nelz · Posted: Sun Sep 30, 2012 7:19 pm Post subject:

el chapulín · Joined: Fri Sep 07, 2012 2:13 pm Posts: 50

As it's a Debian based distro this should do it:

heiowge · Posted: Mon Oct 01, 2012 3:55 pm Post subject:

CONFIG_CPU_FREQ=y
CONFIG_CPU_FREQ_TABLE=y
CONFIG_CPU_FREQ_STAT=y
CONFIG_CPU_FREQ_STAT_DETAILS=y
CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
# CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE is not set
CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
CONFIG_CPU_FREQ_GOV_POWERSAVE=y
CONFIG_CPU_FREQ_GOV_USERSPACE=y
CONFIG_CPU_FREQ_GOV_ONDEMAND=y
CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
_________________
AMD PHENOM II X6, 14 GB DDR3, 500 GB hd, 1GB nVidia card, running Linux Mint 14 KDE / Win 7. Damn thing keeps breaking.

eeepc 1015PX, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd running Mint 14 MATE. Running great.

el chapulín · Joined: Fri Sep 07, 2012 2:13 pm Posts: 50

Well the performance governor is configured as the default on that system... but you said that different cores are at different speeds, which as far as I know is not normal cpfreq behaviour - nor is it normal for speedstep or cool n quiet as far as I know.

The cores being locked to 800MHz could be a symptom of a lack of "dual power plane" support on the motherboard. You should verify this first and that your board is definitely an AM3 board and not an AM2+ or "AM3 optimised" board... your CPU, assuming it's the one in your signature certainly requires an AM3 board to realise it's full potential, but you haven't stated what motherboard you have.

heiowge · Posted: Mon Oct 01, 2012 8:13 pm Post subject:

Its an ASRock M3A770DE. I hope that means more to you than it does to me. The manual says "Support for socket AM3 processors: AMD Phenom II X4 / X3 / X2 (except 920 / 940) and Athlon II X4 / X3 / X2 processors).
_________________
AMD PHENOM II X6, 14 GB DDR3, 500 GB hd, 1GB nVidia card, running Linux Mint 14 KDE / Win 7. Damn thing keeps breaking.

eeepc 1015PX, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd running Mint 14 MATE. Running great.

heiowge · Posted: Mon Oct 01, 2012 8:25 pm Post subject:

Maybe these will help?

_________________
AMD PHENOM II X6, 14 GB DDR3, 500 GB hd, 1GB nVidia card, running Linux Mint 14 KDE / Win 7. Damn thing keeps breaking.

eeepc 1015PX, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd running Mint 14 MATE. Running great.

el chapulín · Joined: Fri Sep 07, 2012 2:13 pm Posts: 50

Your board is ok. As a diagnostic test can you disable frequency scaling in the BIOS setup (if you're not sure how read the motherboard manual) and see if that causes all cores to return to their correct speed.

Paradigm Shifter · Joined: Sat May 19, 2012 1:16 pm Posts: 84

Set 'Cool 'n' Quiet' to [Disabled]. Watch all CPU cores run at 3200Mhz.

Modern CPUs are designed in such a way as to allow cores to clock independently based on load.

This Anandtech review, particularly the second page, goes into a little more detail about 'Turbo' and power states on the CPU cores.

Was my previous post a figment of my imagination? You're looking for a problem when there isn't one.

el chapulín · Joined: Fri Sep 07, 2012 2:13 pm Posts: 50

He has the performance governor enabled so all cores should at the highest clock, that is the issue.

I agree though, disabling cool and quiet should be the next step.