SystemTAP boot process instrumentation
  ======================================

This directory contains some info about using SystemTAP for probing
file opens, and proces fork & runtimes during boot. These instructions
were put together while using Fedora Core 5, Test 2, which has a build
of SystemTap 0.5.2-2

 1. Generate the SystemTAP binary probe

       stap -g -k -p 4 initprocs.stp

    NB I only need '-g' (Guru Mode) here because I wanted to get access
       to some fields in the current task structure - don't use -g unless
       you really need it

 2. Move the generated kernel module somewhere safe

       mv /tmp/stapUf342/stap_2433.ko /boot/stap/initprocs.ko

 3. Copy the init-stap.sh script into place

       cp stap-init.sh /boot/stap/init.sh

 4. Reboot and at the GRUB menu, select the desired kernel and
    set it to use a custom init script, by pressing 'a' and then
    entering 'init=/boot/stap/init.sh' 

 5. ...wait for startup to complete...

 6. Login & tell systemtap daemon to shutdown

      killall stpd

 7. Copy the logs out of tmpfs to somewhere safe

      cp /boot/stap/data/initprocs.log /root/initprocs.log


Now use Perl to do some reporting on the data collected,

 1. Summarise time of each init script 

    init-time-summary.pl < initprocs.log

 2. Summarise cummulative files read/write for every process
    
    process-summary.pl < initprocs.log

 3. Display proc tree rooted at  'start_udev'

    process-tree.pl start_udev  < initprocs.log

 4. Display time taken by all runs of modprobe 

    process-time.pl modprobe  < initprocs.log

...more...