Log in to post comments. Changes in retired instruction rate may indicate hardware clock cycle modulation. Fri, 4 Oct Where can i find official information? At least some processors will support frequencies below the “maximum efficiency” frequency, but I don’t know if the Power Control Unit will use these or switch to duty cycle modulation Section

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Power Capping Framework and RAPL Driver []

Leave a Comment Please sign in to add a comment. For more complete information about compiler optimizations, see our Optimization Notice. If the power limit is still exceeded at the “maximum efficiency” frequency typically 1.

Also there are other technologies available, for power capping various devices.

Setting DVFS to 1. While staying below a power limit, it allows devices to automatically adjust performance to meet demands – Dynamic control and re-budgeting: I seem to recall one case with severe thermal throttling that was running very slowly as if duty cycle modulation was being nitelbut I never saw any changes to the corresponding MSRs.

Log in to post comments. Changes in retired instruction rate may indicate hardware clock cycle modulation. Article Overview With the evolution of technologies, which enables power monitoring and limiting, more and more devices are able to constrain their power consumption under certain limits.

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My questions is how RAPL caps the power. Power Capping framework is an effort to have a ppwer interface available to Linux drivers, which will enable – A uniform sysfs interface for all devices which can offer power capping – A common API for drivers, which will avoid code duplication and powrr implementation of client drivers. If the power limitation is low, it manipulates clock duty cycles.

Each device can report its power consumption. I can conform your observation with compute-bound applications. Skip to main content.

RAPL power capping: how does it work

At least some processors will support frequencies below the “maximum efficiency” frequency, but I don’t know if the Power Control Unit will use these or switch to duty cycle modulation Section Added to drivers build bitops: If power cap is set to 45 watts no DVFS and turbo boost is onthe observed frequency is more or less 1. With a low power cap, the perfromance is very bad.

I read through the two sections in the manual, still I’m not very clear what is the difference between duty cycle modulation and clock cycle modulation? Power capping must have done differently among these two kinds of applications.

Add class driver PowerCap: One possible interpretation is that the MSRs show software-controlled duty-cycle modulation, but may not show hardware-initiated duty-cycle modulation.

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Someone told me, if the power cap is high, it does DVFS. Hello, i’m looking at performance variations of my application under a range of power caps. Setting power cap directly to 75 watts no DVFS and turbo boost is onthe frequency is 1.

There are several use cases for such technologies: Where can i find official information? Depending on poweg processor, another place to look for DVFS is in the “uncore” clock.

Soon it is very likely that other vendors are also adding or considering such implementation. With a high power cap, the performance is reasonable. Fri, 4 Oct Setting power limits on the devices allows users to guard against platform reaching max system power level.

If each device can be constrained to some power, extra power can inel to other devices, which needs additional performance.

I checked duty cycling and clock modulation.