Ubuntu Wiki

• Launchpad Entry: compcache-usage

• Created: June 23, 2008

• Contributors: Tim Gardner

• Packages affected: linux, casper

Summary

The compcache patch allows for compressed swap space in RAM. This allows for a smaller footprint on constrained memory setups. This is of special interest for LiveCD and LTSP.

Release Note

Improved memory usage for LiveCD on small memory configurations.

Rationale

Because there is no swap space on LiveCD's, physical memory requirements are not comparable to an actual installed system. More memory is needed for the install than is needed for the running and installed system.

Compressed RAM based swap would service to alleviate this constraint.

Use Cases

Bob wants to use some old computers with 256Megs of memory for Ubuntu desktops at the school where he works. Because he is using a LiveCD with compcache, he is able to boot the LiveCD.

Sally wants to setup some LTSP system, which cannot have physical swap, and have limited physical memory. Using compcache, these systems would still be usable, running mozilla.

Assumptions

None.

Implementation

Integrate compcache into the kernel. There is a clean patch for our intrepid kernel at http://code.google.com/p/compcache/

Once this is in place, casper scripts will need to setup the compcache swap space on boot. Most likley it will only need to do so when physical memory is < 512Megs.

Test/Demo Plan

Can be tested pretty easily using a virtual machine and allocating 256Megs of RAM to it.

CategorySpec CategoryKernel