Processors (Intel® Core™, Intel® Xeon®, etc); processor utilities and programs (Intel® Processor Identification Utility, Intel® Extreme Tuning Utility, Intel® Easy Streaming Wizard, etc.)
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RAPL DRAM energy units confusion for some CPUs


Hi, I have a couple of questions on RAPL DRAM energy units, per the MSR_DRAM_ENERGY_STATUS register. The Software Developer's Manual, Volume 4 indicates that some processors use a non-standard 15.3 uJ energy unit for DRAM instead of using what's specified in the MSR_RAPL_POWER_UNIT register.

As of March 2018, the SDM does NOT appear to specify 15.3 uJ for Xeon Phi CPUs (Family_Models 06_57H and 06_85H in Section 2.17), but the community consensus seems to be that these two processors do in fact use 15.3 uJ as their energy unit (see the Linux kernel, PCM, PAPI).

The Xeon D (Family_Model 06_56 in Sections 2.14 - 2.15.1), through inheritance from Table 2-35, claims to use the 15.3 uJ DRAM energy unit, but the community seems split on what it really is (e.g., the Linux kernel does NOT use the 15.3 uJ unit configuration).

Please provide clarification on what DRAM energy unit configuration these processors really use and if/when we can expect any corrections to the Software Developer's Manual.

Much appreciated,


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Hello connorimes,



I understand that you are looking for information about the RAPL DRAM energy units.



Regarding this, I would recommend you to direct the inquiry to our developer's zone support. You can actually register and enter the communities there for support since this question is something supported by them, please refer to the link below:






David V