Due 10/6/06.
Start with the stripped version of the standard 2.6 scheduler:
http://www.oslab.info/uploads/Labs/sched.c.txt
(sorry about the .txt endings on everything - it's because of the wiki we are using)
Make the following modifications to isolate all scheduler-specific code:
1. 'struct runqueue' - Take active, expired, and arrays[] out
of this structure and put them into one called struct runqueue_ingo,
then replace them with:
struct runqueue_ingo ingo;
Put them into runqueue_ingo and put it in the file sched-ingo.h
Get the code to compile and run. You may want to use the following trick:
put a '_' in front of each field in runqueue_ingo
(i.e. _active, _expired)
define the old names to be ingo._name:
#define active ingo._active
#define expired ingo._expired
NOTE - you might wish to skip this, as it will cause more trouble for the rest of the assignment than it avoids here
2. Modify schedule() around line 1194 (switch_tasks:) to call a new function that determines the next task:
next = get_next_task(rq, now)
In particular, this will replace all the code from
idx = sched_find_first_bit(...
up through the label switch_tasks:.
Get this version to compile and run.
3. Remove all the code in sched_setscheduler and replace it with 'return 0'. Move get_next_task, activate_task, deactivate_task, resched_task, and schedule_tick to the file sched-ingo.c, along with all the functions they call.
Get it to compile and run.
Check that you can boot and run a kernel compile on the new kernel.