Proposals

Page reclaim challenges with cgroup based resource controller

This proposal has been rejected.

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One Line Summary

Page reclaim challenges on container with isolation and scalability.

Abstract

A good page replacement algorithm introduces minimum page-fault on the system. So the goal is to keep the “right” page in memory which will be accessed soon. It is difficult since each process has different memory access pattern. Also each type of memory pool has different properties to work with. Considering efficiency and scalability, Linux uses Least Recently Used (LRU) along with Page Aging(PG_referenced).

Cgroup and resource controllers in Linux are used to provide resource isolation of a group of processes. A memory controller allows us to monitor and limit the resident set size (RSS) of a cgroup. The infrastructure provided for memory isolation adds a new dimension to the existing page reclaim logic. Each cgroup maintains its own page LRU lists. Per-cgroup background reclaim(kswapd) is triggered based on different memory pressure rate. Lock contention is one of the challenges working with multiple kswapd threads. Not only user pages, the kernel slabs needs to be isolated as well and changes are needed to existing slab shrinkers. Page reclaim also relays on the dirty pagecache writeout and it might cause system OOM with different filesystem writeout strategies.

This talk will present our current page reclaim solution based on the existing cpusets and fake numa mechanism, and discuss about the challenges we faced and issues remained. Also we will discuss about the ideas to how to do efficient page reclaim on per-page memory controller based system.

Tags

Linux, memory management, page reclaim, container

Speaker

  • Profile

    Biography

    Ying is a Stony Brook University graduate (2006) who now works as an kernel developer with Google production kernel team. Her interests is primarily in memory management subsystem, with focus on improving system resource utilization and scalability.

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