Per-task budget high-resolution timers (hrtimers).

As a step towards implementing more complex budget tracking
method (ex. BWI, VXR, etc.), we need per-task budget trackers
because we may be required to drain budget from a task, even
while it is suspended or blocked.
This patch does:
1) Replaces the per-CPU hrtimers with per-task hrtimers.
2) Plugin architecture for different budget policies.

This patch creates three budget draining policies:
SIMPLE, SAWARE (suspension-aware), and SOBLIV (suspension-oblivious).
However, only SIMPLE is supported by this patch.

SIMPLE (default):
Budget drains while the task is scheduled. Budget is preserved
across self-suspensions (but not job completions, of course).
Only SIMPLE is supported in this patch. (Maintaining current Litmus
functionality.)

SAWARE:
Draining according to suspension-aware analysis. Budget should drain
whenever a task is among the top-m tasks in its cluster, where
m is the number of processors in said cluster. This draining should
happen whether or not the task is actually scheduled.

SOBLIV:
Draining according to suspension-oblivious analysis. Budget should
drain whenever the task is scheduled or suspended (but not due to
preemption). Exception: Draining should halt when we can prove that
the task is not among the top-m tasks blocked on the same lock (i.e.,
on the PQ in the OMLP-family locking protocols).

1 files changed, 2 insertions, 0 deletions

diff --git a/include/litmus/litmus.h b/include/litmus/litmus.h
index 70b421d59d34..f6ea5f6e80ee 100644
--- a/include/litmus/litmus.h
+++ b/include/litmus/litmus.h
@@ -62,6 +62,7 @@ void litmus_exit_task(struct task_struct *tsk);
 #define get_priority(t)         (tsk_rt(t)->task_params.priority)
 #define get_class(t)        (tsk_rt(t)->task_params.cls)
 #define get_release_policy(t) (tsk_rt(t)->task_params.release_policy)
+#define get_drain_policy(t) (tsk_rt(t)->task_params.drain_policy)
 
 /* job_param macros */
 #define get_exec_time(t)    (tsk_rt(t)->job_params.exec_time)
@@ -69,6 +70,7 @@ void litmus_exit_task(struct task_struct *tsk);
 #define get_period(t)           (tsk_rt(t)->task_params.period)
 #define get_release(t)          (tsk_rt(t)->job_params.release)
 #define get_lateness(t)         (tsk_rt(t)->job_params.lateness)
+#define get_budget_timer(t) (tsk_rt(t)->job_params.budget_timer)
 
 #define effective_priority(t) ((!(tsk_rt(t)->inh_task)) ? t : tsk_rt(t)->inh_task)
 #define base_priority(t) (t)