Hello, i’m looking at performance variations of my application under a range of power caps. Skip to main content. Setting DVFS to 1. Leave a Comment Please sign in to add a comment. I seem to recall one case with severe thermal throttling that was running very slowly as if duty cycle modulation was being employed , but I never saw any changes to the corresponding MSRs. There are several use cases for such technologies:
|Date Added:||15 November 2017|
|File Size:||48.74 Mb|
|Operating Systems:||Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X|
|Price:||Free* [*Free Regsitration Required]|
Changes in retired instruction rate may indicate hardware clock cycle modulation. Log in to post comments. Each device can report its power consumption.
Fri, 4 Calping Skip to main content. It is easy enough to monitor the actual unhalted processor cycles to determine the average frequency.
Power Capping Framework and RAPL Driver
Add class driver PowerCap: Article Overview With the evolution of technologies, which enables power monitoring and limiting, more and more devices are able to constrain rwpl power consumption under certain limits.
My questions is how RAPL caps the power. Added to drivers build bitops: Setting power cap directly to 75 watts no DVFS and turbo boost is onthe frequency is 1. 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 I often find it difficult to figure out which parts of Chapter 14 of Volume 3 of the Intel Architectures SW Developer’s Cappimg actually apply to my systems.
I seem to recall one case with severe thermal throttling that was running very slowly as if duty cycle modulation was being employedbut I never saw any changes to the acpping MSRs. For more complete information about compiler optimizations, see our Optimization Notice.
Power Capping Framework and RAPL Driver 
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? With a low power cap, the perfromance is very bad.
If the power limit is still exceeded at the “maximum efficiency” frequency typically 1. While staying below a power limit, it allows devices to automatically adjust performance to meet demands – Dynamic control and re-budgeting: There are several use cases for such technologies: I can conform your observation with compute-bound applications.
With a high power cap, the performance is reasonable. Setting DVFS to 1.
Where can i find official information? Leave a Comment Please sign in to add a comment.
RAPL power capping: how does it work
Soon it is very likely that other vendors are also adding or considering such implementation. If each device can be constrained to some power, extra power can redistributed to other devices, which needs additional performance.
In one instance, I noticed that when running a power-limited application on a Xeon Platinum system, the uncore frequency was reduced by a much larger percentage than the core frequency. One possible interpretation is that the MSRs show software-controlled raol modulation, but may not show hardware-initiated duty-cycle modulation.
Power Capping framework is an effort to have a uniform 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 rpal avoid code duplication and czpping implementation of client drivers.
Intel is slowly adding many devices under RAPL control.
Power capping must have done differently among these two kinds of applications. Also there are other technologies available, for power capping various devices. Setting power limits on the devices allows users to guard against platform reaching max system power level. I checked duty cycling and clock modulation. If power cap is set to 45 watts no DVFS and turbo boost is on caping, the observed frequency is more or less 1.