ThinClientFasterStartup

Revision 6 as of 2005-11-02 00:59:24

Clear message

Summary

Speed up the Thin Client bootprocess for LTSP

Rationale

Ubuntu 5.10 thin clients take ages to boot. Some of the generic startup time improvements will also apply to thin clients, but we should specifically optimize the thin client startup process as well. Thin clients are usually low-spec hardware and need this more than most.

Use cases

Matthew gives a class on usability at university where uses LTSP in his class, if he's te first in the class for the day he needs to plan extra time for booting the Thin Clients for the pupils.

Scope

The bootprocess of LTSP Thin Clients as well as the default bootstrapping of the thin client chroot environment.

Design

  • Rip out the unneeded services from Thin Clients
  • Fix the delay of nfs mounting in klibc
  • Compare the list of started services between LTSP 4.1 and breezy LTSP
  • Remove the "sleep 3" from the initramfs nfs script
  • start LDM as early as possible in the bootprocess
  • find the slowing down part in syslogd (strace) and fix it
  • run a ntpd on the ltsp server and make the thin client pull its time from there
  • make ltsp-build-client's debootstrapping install only the bare minimum needed (probably introduce a thin client mode)
  • drop module-init-tools from the bootprocess
  • find any silent scripts that run and might slow down the bootprocess

Implementation

Cutting down the list of started services in rcS.d on the Thin Client to the following gains us 30 seconds:

  • S02mountvirtfs
  • S04udev
  • S15linux-restricted-modules-common
  • S32ltsp-client-setup
  • S35mountall.sh
  • S36mountvirtfs
  • S36udev-mtab
  • S40hotplug
  • S40networking
  • S50alsa-utils
  • S70xorg-common

This seems to be the bare minimum of needed bootscripts. The bootprocess still needs ~60 seconds from hitting the powerbutton to being able to log in at the loginmanager (which is about as much as a normal ubuntu workstation installation), mostly caused by initramfs and hotplug which should be sped up by changes Scott will make to the initramfs/hotplug architecture.

Code

Changes in ltsp-build-client are required to remove the unneeded startup scripts. initramfs and hotplug changes are covered in other specs. The ltsp-client startscript should move up to the top of rc2.d

Data preservation and migration

Breezy users will either need to rebuild their chroot environment (recommended, since the initramfs/hotplug changes will gain the most speedup) but we could at least provide a script that disables the unneeded services.

Outstanding issues

initramfs/hotplug speedup

BoF agenda and discussion