Total lack of kernel / determinism

• Repeatable runs ?

• • bin daemons, package mgmt, cron etc.
  • boot to a raw / minimal X session
  • $ echo 3 > /proc/sys/vm/drop_caches
  • ioctl(BLKFLSBUF) /dev/*
  • $ time [startup-of-large-app]
  • +/- 10% jitter in startup time is common.

• Why ? no idea. b.k.o#7372 ... - 130+ comments etc.

• • NB. ~no complex elevation / queuing in single application start.
  • Tuning / measuring I/O appears to be a black art
  • Just re-compile your kernel with ...
  • Any new code has to run a gauntlet of uncertainty ...
  • • “Will this break anything ?”