Messages in this thread | | | Date | Wed, 10 Aug 2011 09:59:33 -0700 | Subject | Re: [PATCH] [RFC] ondemand governor: dynamic cpufreq scaling with different CPUs | From | Venki Pallipadi <> |
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On Mon, Aug 1, 2011 at 7:51 AM, Len Brown <lenb@kernel.org> wrote: > Re: software vs hardware coordination > > Speaking for Intel, everything we make, from hand-sets to supercomputers > supports hardware coorination. > > Think about it -- if we did not, then we would not be able > to support a legacy OS that doesn't know how to do SW coordination. > > HW coordiation is the simplest thing for the SW because > SW doesn't have to know anything at all about topology constraints. > It is also the simplest thing for the BIOS, which doesn't have > to correctly describe topology. > > Yes, there is an MSR bit that the BIOS can flip to disable > HW coordination. 90% of the time that bit is set it is a BIOS bug. > eg. the bit is set, but the BIOS fails to properly set up the > ACPI tables to properly enable SW coordination, resulting > in a system with really strange performance issues. > > Indeed, I proposed before, and I will propose again that > the underlying ACPI _PSD support behind SW coordination > be completely removed from Linux. > > Venki, > I recall that you mentioned one platform that depends on it -- > and I'd like to understand that issue and address it with a quirk > rather than expose all systems to BIOS bugs due to bogus _PSD support. >
Agree. Addressing this as a quirk would be fine. The processor that needs it is E74xx series, IIRC.
Thanks, Venki
> Winston, > Your system is running in SW coordination mode? > What do you see if you run with the patch below? > I'd be intersted to see the output from adpidump for your system. > > thanks, > -Len Brown > Intel Open Source Technology Center > > --- > diff --git a/include/acpi/pdc_intel.h b/include/acpi/pdc_intel.h > index 552637b..d081595 100644 > --- a/include/acpi/pdc_intel.h > +++ b/include/acpi/pdc_intel.h > @@ -22,7 +22,6 @@ > > #define ACPI_PDC_EST_CAPABILITY_SWSMP (ACPI_PDC_SMP_C1PT | \ > ACPI_PDC_C_C1_HALT | \ > - ACPI_PDC_SMP_P_SWCOORD | \ > ACPI_PDC_SMP_P_HWCOORD | \ > ACPI_PDC_P_FFH) > > -- 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/
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