Specifically, if software sets the P-state of a CPU core within the turbo range that is, above the turbo threshold , the processor is permitted to take over performance scaling control for that core and put it into turbo P-states of its choice going forward. The governor “performance” may decide which speed to use within this range. C1 often known as Halt is a state where the processor is not executing instructions, but can return to an executing state essentially instantaneously. Sign up using Facebook. The instantaneous energy usage power of the processor is related to its activity.
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C0 is the operating state. In addition to the two good links Ravan gave, see also here and here. Share Tweet Share Send. Now wait a moment. I am a student in aristotel univercity of thessaloniki and i could use the info for a simulation experiment.
Specifically, if software sets the P-state of a CPU core within the turbo range that is, above the turbo thresholdthe processor is permitted to take over performance scaling control for that core and put it into turbo P-states of its choice going forward. The following sequence of shell commands can be used to enable them and see their output if the kernel is generally configured to support event tracing: Both are scaled as the P-state increases.
This is roughly correct. If unset equalt to 0, which is the defaultturbo P-states can be set by the driver.
The maximum turbo P-state that can be pstaate for 3 cores at the same time usually is lower than the analogous maximum P-state for 2 cores, which in turn usually is lower than the maximum turbo P-state that can be set for 1 core. Sign up or log in Sign up using Google.
This processor state is optional. The maximum supported one-core turbo P-state if turbo P-states are supported. Can sombody explain the exact difference between these two drivers, such as the different options they have and how they differ for example, in the powersave option?
Doug Smythies 7, 3 14 In fact, if one of them is set by software, the processor is not expected to change it to a lower one unless in a thermal stress or a power limit violation situation a higher P-state may still be used if it is set for another CPU in the same package at the same time, for example.
What exactly is a P-state? (Pt. 1)
If the HWP feature is enabled in the processorthe resulting effective values are written into its registers whenever the limits change in order to request its internal P-state selection logic to always set P-states within these limits. The same applies for decreasing the frequency.
Would there be a good reason for somebody using trusty to switch to pstate then? When someone refers to a P-state, pstwte only the frequency is talked about. Home Questions Tags Users Unanswered. Which of them will be in effect depends on what kernel command line options are used and on the capabilities of the processor.
However, that permission is interpreted differently by different processor generations.
intel_pstate CPU Performance Scaling Driver — The Linux Kernel documentation
These names are related to the Turbo Boost technology allowing a multicore processor to opportunistically increase the P-state of one or more cores if there is enough power to do that iintel if that is not going to cause the thermal envelope of the processor package to be exceeded. Hi, i am from china.
Note, however, that some of those processors may not be supported. We all know that increasing the frequency, increases a processor’s performance. Sign up using Email and Password. Maximum P-state the driver is allowed to set in percent of the maximum supported performance level the highest supported turbo P-state. One more issue related to that may appear on systems supporting the Configurable TDP feature allowing the platform firmware to set the turbo threshold.
If the processor supports the HWP feature, it will be enabled during the processor initialization and cannot be disabled after that.