Messages in this thread | | | From | Wes Felter <> | Subject | Re: HELP: cpufreq on HT and/or SMP systems | Date | Fri, 01 Aug 2003 17:36:21 -0500 |
| |
On Thu, 31 Jul 2003 23:53:54 +0200, Ricardo Galli wrote:
> I have some doubts regarding cpufreq for SMP systems (for developing > http://mnm.uib.es/~gallir/cpudyn/). > > If I remember well, I read a while ago that cpufreq didn't work in SMP > systems, but reading the docs and kernel/cpufreq.c, it seems there should be > any problem? > > Is it true? > > OTH, I trying it on a P4 HT, and it works, changes in the frequency of one of > the "cpu's", changes both.
That makes sense, since the CPU only has one clock.
> What happens in the case of several real cpu's? Does it keep the same > frequency for every cpu? According to a comment in cpufreq.c, it seems that > each cpu might have different frequencies.
AFAIK no SMP systems have voltage/frequency scaling (SpeedStep/PowerNow). I've heard that ACPI P-states works on SMP, but if it's not doing voltage/frequency scaling then I don't know what it's doing.
Wes Felter - wesley@felter.org - http://felter.org/wesley/
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |