Stap scripts to track task cpu changes

[William Cohen]

Ankita Garg wrote:
> Hello folks,
> 
> Quite sometime back, I was faced with a situation where I needed to
> track instances when a particular task was being migrated away from a
> cpu. I used the following trivial script. The tid needs to be passed as
> parameter. Sharing it, hoping it might be useful for some folks.

I would like to add these example to the systemtap examples. I have looked
through them and made some tweaks. For both of them I formatted them not to use
tabs so they can used in documentation.

For chng_cpu.stp use the appropriate probe point, scheduler.cpu_on.  Why the
check for "tid() != 0"?

For migrate.stp The check "$1 != 0" seemed to be unneeded. Was there a reason
for using $p->pid and kernel_string($p->comm) rather tid() and execname()?  The
test is using "tid() == $1"

-Will



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