Hacker News Reader

Please see https://news.ycombinator.com/item?id=47719489 and stop posting like this to HN.

https://news.ycombinator.com/item?id=47681703 was even worse; definitely please stop posting like that to HN.

Nope, there isn’t a tradeoff; median latency isn’t affected. I don’t think you understand the code. The p50 is identical between a single read and the hedged strategy.

The clflush is there because the technique targets data that will miss the cache anyway. If your working set fits in L1, you don’t need this.

Also, AWS Graviton instances absolutely do not expose per-channel memory controller counter PMUs. That’s why you have to use timing-based channel discovery.

The IBM z-system is neat! But my technique will work on commodity hardware in userspace, and you can easily only sacrifice half the space if you accept 2-way instead of 8+ way hedging. It’s entirely up to you how many channel copies you want to use.

Your reply was quite rude, but I hope this is informative.

I was just trying to reconcile his reply with the charts. Have you tested how this scales down for smaller systems, as one might find in on the management side of a network switch?

The video was about how rowhammer works, the lib was byproduct.