>>> On 14.03.12 at 00:18, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote: > The purpose of these patches is two-fold: > 1) Remove weird performance issues encountered in the field where the > Linux kernel cpufreq scaling drivers would change the P-states while the > Xen hypervisor would do the same. > 2) Provide a runtime knob from within the kernel to disable the cpu > frequency > API (akin to the behavior of "#CONFIG_CPU_CPUFREQ is not set"). Acked-by: Jan Beulich <jbeulich@xxxxxxxx> (Albeit I'd recommend using 'bool' for the variable and function return types in the first patch.) > The patches are based on the mechanism that Len Brown came up for the > cpuidle > drivers - where there is a disable_cpuidle() call. His patches also provided > a module parameter - but I wasn't sure whether that is something you would > want. > (for reference, Len's patch is d91ee5863b71e8c90eaf6035bff3078a85e2e7b5) > > The other way of disabling the cpufreq scaling drivers from being invoked > is by thwarting the cpufreq drivers from loading by influencing their > startup > checks. For powernow-k8 that is easy - disallow the RDMSR (and that is > currently > happening). For acpi-cpufreq I am not sure what could be done - the calls it > makes are to the ACPI libraries which we need for other uses. > > Another solution I thought off was to provide a cpufreq governor that would > be a nop, and hence end up not calling the cpufreq scaling drivers. But that > just seems heavy-handed and I am not sure how the decision of when to load it > (and set it) would be done. > > arch/x86/xen/setup.c | 1 + > drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++++++++ > include/linux/cpufreq.h | 2 ++ > 3 files changed, 27 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
