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Server Gurus Discussions

Journeyman III

AMD CPU supporting software-based runtime memory timing parameter control?

Hello community, I'm architectural researcher newbie who's been peeking into stuff like DRAM.

Upon skimming through various research paper, I came across this very interesting paper, named

   "Adaptive-Latency DRAM: Optimizing DRAM Timing for the Common-Case" by Donghyuk Lee et al.

In this paper, there's a sentence at the first paragraph of section 8, quote:

   "We chose this system for its AMD processor, which offers dynamic software-based control over DRAM timing parameters at runtime"

and referenced two technical documents published by AMD.

Now, strange part was, I always thought changing the memory timing parameters such as tCL, tRAS is not supported by any CPUs. In fact, setting these parameters were done between the BIOS and memory; at the startup of the system, even before CPU even kicks in. Yet that paper seemingly says it's possible to change those parameters during runtime, at the software level, without system reboot. What am I missing here? Did old Opteron CPUs really had those features? It would be really helpful for my research experiment if I didn't have to reboot every time and go into BIOS whenever I have to meddle with memory timings.

I know Ryzen Master has the feature to tweak memory settings at the software level, but it requires system reboot to apply the settings, and there seems to be compatibility issue with the settings set by BIOS.

Any info would be of great help. Thanks in advance.

p.s. My personal system is 3900x, go AMD!

1 Reply

AMD Server Gurus community might be better place to ask this query, hence I'm moving it there.