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Dynamic RAM Refresh Analysis

1 post · Nov 2018

What this trail covers

This post details the analysis of dynamic RAM refresh cycles and their measurable impact on system performance from userspace. It introduces techniques for detecting subtle hardware behaviors through software experiments and signal processing (FFT), demonstrating that even low-level hardware operations can be observed and analyzed, leading to potential security insights and performance optimizations.

All Cloudflare trails
  1. Every 7.8μs your computer’s memory has a hiccupThis post introduces a novel method for measuring dynamic RAM refresh delays from userspace. It details the experimental setup involving tight C loops, cache flushing, and precise timing measurements. The core contribution is the application of Fast Fourier Transform (FFT) to noisy timing data to identify the characteristic frequency of DRAM refresh cycles (approximately 128kHz), correlating it with hardware refresh times (tREFI). The post also provides open-source tools for replicating the experiment.