topic Re: DRAM RAPL Issue in Mobile and Desktop Processors

DRAM RAPL Issue

vvaib — Mon, 14 Sep 2015 15:46:33 GMT

Hi,

I am using a Xeon E5 1650 processor for my work and I have been trying to set the power limits for the DRAM through RAPL MSR's. There are no issues when I try to read the DRAM power consumption but

when I write the power limits to to MSR_DRAM_POWER_LIMIT (0x618), there is no change in the DRAM power consumption.

I tried to check the BIOS settings and I am attaching couple of images that I found. Apparently, there is an option DRAM RAPL MODE and it's value can be choses as ) Off 2) Mode 0 and 3) Mode 1.

By default, the value was Mode 1. Can anybody tell me what exactly is the difference b/w these two modes. Also, what changes do I have to do to make the DRAM power limiting work?

Thanks

Re: DRAM RAPL Issue

IUman — Wed, 16 Sep 2015 22:48:56 GMT

Hello kakarrot,

You can get better support at:

Software.intel.com

Re: DRAM RAPL Issue

Cesar_B_Intel — Fri, 18 Sep 2015 07:07:35 GMT

Hello kakarrot,

The BIOS sets DDR RAPL mode though BIOS-to-Pcode Mailbox command. In this case you may Set DRAM only, the power consumption of the main memory.

In regards to DRAM RAPL modes you have two options: DRAM RAPL MODE0=DRAM power from pure activity based estimation and DRAM RAPL MODE1= DRAM power from scaling activity-based estimation to match DDR VR total power (based on VR12 IOUT register)

Regards,

Caesar B.