Kernel module + userspace utils to replay swap events.

Introduction

A kernel module records swap-in/out events and dump them to userspace. We then use this data to simulate same swapping activity in userspace.

Information dumped is:

<sector no.> <R/W bit> <compressed length>

<compressed len> - On every swap-out, page is compressed and its compressed length is noted.

We do not require actual data itself, so its not dumped.

Purpose

This provides lots of data required for development/testing of Allocators and Compression algorithms.

Details

compcache project compresses and stores swap pages in memory. The most challenging part of project is to design allocator than can efficiently store these variable sized compressed pages.

Simulating swapping activity allows us to see allocator behavior in userspace itself. This is much more friendly than rebooting, setting up workload to trigger swapping again and again. Also, gradual improvements to allocator will be easier to develop/debug in userspace.

See: SwapReplayDesign - This also explains usage.