LiveCDPerformance

Revision 12 as of 2005-04-26 05:48:59

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Live CD Performance

Status

Introduction

The boot time for the Ubuntu live CD should be comparable (or superior) to other popular live CDs.

Rationale

The better the load time, the better the liveCD experience, the greater chance an end user will want to use it and move on to installing Ubuntu or another distro.

Scope and Use Cases

Implementation Plan

Performance issues in two areas:

1) Installer

  • Can generation of locales be made faster?

The LiveCDPrompts looking after eliminate some unnecessary questions in the boot process. Language, keyboard layout and so on are some of them.

If we already now this stuff we save time from the input data and the reconfiguring of packages.

A possible solution is placing a localised version on the mirrors. For example, Spanish mirror with Spanish localised Live CD, and so on.

Generic CD required - we need to be able to ship them to the rest of the world.

  • Background things like network setup?

We don't actually need setup the network at the beginning

2) Post-di boot

  • Readahead configuration may be suboptimal

Seems not very helpful. See this experiment on Knoppix (the same compress filesystem: cloop): http://unit.aist.go.jp/itri/knoppix/readahead/index-en.html

  • Do we need gdm?

GDM takes a lot of memory (what we need during the live session to run the applications) and takes a lot of time to run. We could run the /etc/alternatives/x-session-manager instead of the GDM

GDM takes a negligible amount of memory. Someone needs to time X startup with and without GDM.

  • The dma activations help, but no so much
  • We need check out the filesystem compression(whichever we want to use: cloop, squashfs...) performance. But seems this is not the main problem.
  • Check out if we run unnecessary services at the distribution boot time

Nope. There's nothing significant that we can remove.

  • Somebody did a comparative between the official Kubuntu live CD and the same content of the image but compress with Squashfs instead of cloop and unionfs instead of device-mapper. Also he used the [http://metadistros.hispalinux.es Metadistros] live system. The result was the second one takes 50 sec less than Kubuntu to boot.

http://listas.hispalinux.es/pipermail/metadistros-dev/2005-April/000580.html

NEEDS INSTRUMENTATION - do we have detailed enough logfiles?

IMPLEMENTATION:

1) Full timings for initial install and second-stage boot. 2) For packages that spend an extended amount of time in configure, see if that can be improved 3) Investigate whether dropping gdm makes a significant difference to startup time 4) Test different filesystems 5) Investigate the interaction of readahead with the current compressed filesystem - are we spending more time seeking than we'd spend just loading the programs anyway?

Data Preservation and Migration

Packages Affected

User Interface Requirements

Outstanding Issues

UDU BOF Agenda

  • d-i performance
  • casper performance

  • Ubuntu boot performance (FasterBoot)

UDU Pre-Work

  • Profile the live CD boot sequence to measure the time taken for each step
    • d-i startup (time-to-first-question)
    • Pre-casper d-i activity (measured per menu entry)
    • Casper d-i activity (measured per casper.d script)
    • Standard boot sequence