Software Tuning, Performance Optimization & Platform Monitoring
Discussion regarding monitoring and software tuning methodologies, Performance Monitoring Unit (PMU) of Intel microprocessors, and platform updating.

DRAM RAPL on Haswell-EP


I have a Xeon E5-1620 v3 processor on a Supermicro X10SRA motherboard.

I'm trying to measure the DRAM energy consumption on Linux using the Intel Performance Counter Monitor software, specifically the PCM-power utility. In the BIOS(pdf), there's a setting for "DRAM RAPL Baseline Mode" which gives three options: "Disabled", "DRAM RAPL Mode 0", and "DRAM RAPL Mode 1". The Intel Power Governor README says that Mode 1 is "the VR (voltage regulator mode of power estimation)". Can someone explain to me what the difference is between Mode 1 and Mode 0? When I set it to Mode 1, pcm-power reports zero DRAM energy. I can set it to Mode 0 and the energy is reported correctly. Why am I able to measure DRAM energy consumption in one mode but not the other? My intuition tells me that something may be wrong (either damaged or configured incorrectly) about the voltage regulator on my part, eliminating the ability to make these energy measurements.

Thanks for your help!


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