tailslayer

This is a 54 minute video. I watched about 3 minutes and it seemed like some potentially interesting info wrapped in useless visuals. I thought about downloading and reading the transcript (that's faster than watching videos), but it seems to me that it's another video that would be much better as a blog post. Could someone summarize in a sentence or two? Yes we know about the refresh interval. What is the bypass? Update: found the bypass via the youtube blurb: https://github.com/LaurieWired/tailslayer "Tailslayer is a C++ library that reduces tail latency in RAM reads caused by DRAM refresh stalls. "It replicates data across multiple, independent DRAM channels with uncorrelated refresh schedules, using (undocumented!) channel scrambling offsets that works on AMD, Intel, and Graviton. Once the request comes in, Tailslayer issues hedg

This is very much worth watching. It is a tour de force. Laurie does an amazing job of reimagining Google's strange job optimisation technique (for jobs running on hard disk storage) that uses 2 CPUs to do the same job. The technique simply takes the result of the machine that finishes it first, discarding the slower job's results... It seems expensive in resources, but it works and allows high priority tasks to run optimally. Laurie re-imagines this process but for RAM!! In doing this she needs to deal with Cores, RAM channels and other relatively undocumented CPU memory management features. She was even able to work out various undocumented CPU/RAM settings by using her tool to find where timing differences exposed various CPU settings. She's turned "Tailslayer" into a lib now, available on Github, https://github.com/LaurieWired/tailsla