cpu scaling questions
Thomas J. Baker
tjb at unh.edu
Mon Oct 2 19:44:02 UTC 2006
On Mon, 2006-10-02 at 12:01 -0400, Dave Jones wrote:
> On Mon, Oct 02, 2006 at 09:45:27AM -0400, Thomas J. Baker wrote:
> > I've got two questions related to cpu scaling. On my laptop I've got a
> > Core 2 Duo. Can the two cores scale frequencies independently?
> No. Think about it. You have a single package, with a single power source.
> > Most of
> > the time that doesn't seem like the case but every once in a while, my
> > cpufreq applets show different speeds. I'm assuming that there is just a
> > bit of slop involved and the two cores are always the same speed.
> It's a bug, but it should be cosmetic only. It's on the TODO, but
> there are a number of other issues in this code that need tackling
> first before it gets clean enough to fix this properly.
> FC6-update/FC7 stuff.
> > On my desktop, I've got Xeon CPUs that support limited scaling; they run
> > at either 2.8 or 3.4GHz. On FC5, they used to scale on demand but under
> > FC6 they don't and the cpufreq applet has a manual setting for 2.8 or
> > 3.4 with an automatic setting that is greyed out.
> Which cpufreq driver were they using ?
> File a kernel bug, and attach dmesg.
Just curious - it must also a bug that under FC5, with two hyperthreaded
Xeon CPUs, all four logical processors scale independently?
I looked at my FC5 setup and had specified "DRIVER=acpi-cpufreq"
manually. Doing this for FC6 made the scaling behave like FC5,
automatically scaling up for load.
| Thomas Baker email: tjb at unh.edu |
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