Hello, Antti P Miettinen <amiettinen@xxxxxxxxxx> writes: > This is a continuation to "RFC: CPU frequency min as PM QoS param" > patchset. This patchset adds CPU frequency maximum as a PM QoS > parameter and modifies CPU frequncy core to enforce the limit. CPU > frequency ceiling can be used to improve the energy efficiency of > workloads that would cause the cpufreq governors to enforce an > unnecessarily high operating point. In other words, CPU frequency > maximum can act as an energy efficiency level request. > > Tested on Dell E6420 with the ACPI cpufreq driver against Ubuntu > 3.2. Patches are against linux-next, compile tested. I know there were some earlier discussions about the usefulness of a max frequency QoS parameter, so I wanted to throw in a reason to include max as well as min frequency parameters. IMO, having a max frequency QoS parameter would be very useful from a thermal perspective. There are some ongoing projects in the PM working group at Linaro that are exploring plugins to the thermal framework that implment a "cooling device" by capping CPU frequency. Having a QoS parameter do do this would be the logical interface. I also agree with some earlier requests that these should probably be per-CPU instead of global. That would make it simple to cap frequency of one cluster while leaving another alone. Kevin -- 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
