Systemtap on OLPC laptop

Systemtap on OLPC laptop

[William Cohen]

The One Laptop Per Child laptop (http://wiki.laptop.org/go/One_Laptop_per_Child) 
is a small machine designed running Linux (based on Fedora Core) to be 
manufactured inexpensively. Because of the constraints of the machine 512MB 
flash storage, 128MB DRAM, and 366MHz x86 processor, the developers working on 
the machine have been very interested in getting performance tools that point 
them to performance issues. Chris Ball set it up so they are regularly running 
systemtap as a part of the tinderbox build to gage performance (performance link 
on each of the tinderbox builds):

http://learn.laptop.org/tinderbox/

The systemtap script being run is based on the Daniel Berrange's bootprobe work:

http://people.redhat.com/berrange/systemtap/bootprobe/

They have some information on systemtap on the wiki:

http://wiki.laptop.org/go/Systemtap

Right now they have a hacked version of SystemTap generating the kernel modules 
because of the architecture test in the kernel module. SystemTap translator uses 
the build machine's architecture rather than the target when the module is built 
the expected architecture is "i686", but on OLPC machine the kernel is a "i586" 
kernel. Chris Ball mentioned that they would really like to be able to use the 
stock SystemTap rpms from Fedora.

I hacked the translator with the patch that Chris Ball made to skip the 
architecture tests. I have been able to run systemtap modules built with this 
modified systemtap translator. there is a bugzilla, #4186 that mentions the issue.

-Will