4 ms·
An OT hint to the author: I noticed that your RAM runs at 3800, that leads to a mismatch with the Infinity Fabrics' clock of 1800, i.e. increased latency. Ther
by scns 4y ago
An OT hint to the author: I noticed that your RAM runs at 3800, that leads to a mismatch with the Infinity Fabrics' clock of 1800, i.e. increased latency.
There are two solutions to this:
Raise the FCLK (Fabric Clock) to 1900. This should be well tolerated by a Ryzen from the 5000 line.
Lower the RAM clock to 3600 and set sharp sub timings. This will take a little more time but this tool [0] will help. Runs on Windows though, i have an old partition around for stuff like this, dunno if a VM will do. RAM OC became a time consuming hobby for some people, the rabbit hole...
[0] https://www.techpowerup.com/download/ryzen-dram-calculator/ https://www.techpowerup.com/download/ryzen-dram-calculator/
(edit) add sentence bout windows
- strager 4y ago> Raise the FCLK (Fabric Clock) to 1900. Hmm, I think I did this, or something like this. I'llcheck tomorrow. (If I did, then my comment about not overclocking the CPU is misleading!)
- Arch-TK 4y ago>[0] https://www.techpowerup.com/download/ryzen-dram-calculator/ https://www.techpowerup.com/download/ryzen-dram-calculator/ Why on earth is this a binary program? Is there a document online which explains the maths or just implements it in javascript? I don't feel like spinning up a windows VM just to do this kind of calculation.
- scns 4y agoThe author links a google sheet somewhere where he draws the values from. It is several miles long ;)
- strager 4y agoCurrent settings according to BIOS: Target CPU Speed: 3400MHz Target DRAM Frequency: 800MHz Target FCLK Frequency: 1800MHz DRAM timings: 19/20-19-19-19-39 (The DRAM CAS# Latency setting is set to 19, but "CHA" and "CHB" show 20. I don't know what this means exactly.) So I think you're right, scns. I was not getting the best performance. --- I changed FCLK to 1900MHz and re-ran the Linux C++-vs-Rust benchmarks. Some results: build+test w/o deps: 1847ms Rust, 1874ms C++ --> 1801ms Rust, 1837ms C++ incremental test-utf-8: 288ms Rust, 358ms C++ --> 280ms Rust, 350ms C++ So I did get a performance win for both C++ and Rust builds by fixing my FCLK. Thanks!