Enabling DDR segments on demand during memory pressure for DDR power reduction
summary
A userspace C++ daemon registers to PSI and signals a kernel driver that uses memory hotplug to dynamically offline/online 1 GB DDR blocks, turning OFF self/auto-refresh via PASR or full-rank-down. Events use PSI thresholds (examples: 50 ms and 200 ms) and Android intents (screen off, Doze) to escalate priority; measured online latency is ~200 μs, savings scale roughly linearly and become large on 24+ GB devices as unused segments stay collapsed until pressure rises.
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chapters (6)
- 0:00Introduction and motivation
- 2:51When to offline and online segments
- 5:21Memory pressure detection with PSI
- 8:10System design and components
- 9:35Offline and online workflow
- 11:21Power savings and Q&A
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