Add basic generic reservation-based scheduling infrastructure

2 files changed, 226 insertions, 0 deletions

diff --git a/include/litmus/polling_reservations.h b/include/litmus/polling_reservations.h
new file mode 100644
index 000000000000..9958a92b8aeb
--- /dev/null
+++ b/include/litmus/polling_reservations.h
@@ -0,0 +1,37 @@
+#ifndef LITMUS_POLLING_RESERVATIONS_H
+#define LITMUS_POLLING_RESERVATIONS_H
+
+#include <litmus/reservation.h>
+
+struct polling_reservation {
+        /* extend basic reservation */
+        struct reservation res;
+
+        lt_t max_budget;
+        lt_t period;
+        lt_t deadline;
+        lt_t offset;
+};
+
+void polling_reservation_init(struct polling_reservation *pres, int use_edf_prio,
+        int use_periodic_polling, lt_t budget, lt_t period, lt_t deadline, lt_t offset);
+
+struct lt_interval {
+        lt_t start;
+        lt_t end;
+};
+
+struct table_driven_reservation {
+        /* extend basic reservation */
+        struct reservation res;
+
+        lt_t major_cycle;
+        unsigned int next_interval;
+        unsigned int num_intervals;
+        struct lt_interval *intervals;
+};
+
+void table_driven_reservation_init(struct table_driven_reservation *tdres,
+        lt_t major_cycle, struct lt_interval *intervals, unsigned int num_intervals);
+
+#endif
diff --git a/include/litmus/reservation.h b/include/litmus/reservation.h
new file mode 100644
index 000000000000..d8d6ce37dc47
--- /dev/null
+++ b/include/litmus/reservation.h
@@ -0,0 +1,189 @@
+#ifndef LITMUS_RESERVATION_H
+#define LITMUS_RESERVATION_H
+
+#include <linux/list.h>
+#include <linux/hrtimer.h>
+
+struct reservation_client;
+struct reservation_environment;
+struct reservation;
+
+typedef enum {
+        /* reservation has no clients, is not consuming budget */
+        RESERVATION_INACTIVE = 0,
+
+        /* reservation has clients, consumes budget when scheduled */
+        RESERVATION_ACTIVE,
+
+        /* reservation has no clients, but may be consuming budget */
+        RESERVATION_ACTIVE_IDLE,
+
+        /* Reservation has no budget and waits for
+         * replenishment. May or may not have clients. */
+        RESERVATION_DEPLETED,
+} reservation_state_t;
+
+
+/* ************************************************************************** */
+
+/* Select which task to dispatch. If NULL is returned, it means there is nothing
+ * to schedule right now and background work can be scheduled. */
+typedef struct task_struct * (*dispatch_t)  (
+        struct reservation_client *client
+);
+
+/* Something that can be managed in a reservation and that can yield
+ * a process for dispatching. */
+struct reservation_client {
+        struct list_head list;
+        dispatch_t dispatch;
+};
+
+
+/* ************************************************************************** */
+
+/* Called by reservations to request state change. */
+typedef void (*reservation_change_state_t)  (
+        struct reservation_environment* env,
+        struct reservation *res,
+        reservation_state_t new_state
+);
+
+/* The framework within wich reservations operate. */
+struct reservation_environment {
+        lt_t time_zero;
+        lt_t current_time;
+
+        /* services invoked by reservations */
+        reservation_change_state_t change_state;
+};
+
+
+/* ************************************************************************** */
+
+/* A new client is added or an existing client resumes. */
+typedef void (*client_arrives_t)  (
+        struct reservation *reservation,
+        struct reservation_client *client
+);
+
+/* A client suspends or terminates. */
+typedef void (*client_departs_t)  (
+        struct reservation *reservation,
+        struct reservation_client *client,
+        int did_signal_job_completion
+);
+
+/* A previously requested replenishment has occurred. */
+typedef void (*on_replenishment_timer_t)  (
+        struct reservation *reservation
+);
+
+/* Update the reservation's budget to reflect execution or idling. */
+typedef void (*drain_budget_t) (
+        struct reservation *reservation,
+        lt_t how_much
+);
+
+/* Select a ready task from one of the clients for scheduling. */
+typedef struct task_struct* (*dispatch_client_t)  (
+        struct reservation *reservation,
+        lt_t *time_slice /* May be used to force rescheduling after
+                            some amount of time. 0 => no limit */
+);
+
+
+struct reservation_ops {
+        dispatch_client_t dispatch_client;
+
+        client_arrives_t client_arrives;
+        client_departs_t client_departs;
+
+        on_replenishment_timer_t replenish;
+        drain_budget_t drain_budget;
+};
+
+struct reservation {
+        /* used to queue in environment */
+        struct list_head list;
+
+        reservation_state_t state;
+        unsigned int id;
+
+        /* exact meaning defined by impl. */
+        lt_t priority;
+        lt_t cur_budget;
+        lt_t next_replenishment;
+
+        /* interaction with framework */
+        struct reservation_environment *env;
+        struct reservation_ops *ops;
+
+        struct list_head clients;
+};
+
+void reservation_init(struct reservation *res);
+
+/* Default implementations */
+
+/* simply select the first client in the list, set *for_at_most to zero */
+struct task_struct* default_dispatch_client(
+        struct reservation *res,
+        lt_t *for_at_most
+);
+
+/* "connector" reservation client to hook up tasks with reservations */
+struct task_client {
+        struct reservation_client client;
+        struct reservation* reservation;
+        struct task_struct *task;
+};
+
+void task_client_init(struct task_client *tc, struct task_struct *task,
+        struct reservation *reservation);
+
+#define SUP_RESCHEDULE_NOW (0)
+#define SUP_NO_SCHEDULER_UPDATE (ULLONG_MAX)
+
+/* A simple uniprocessor (SUP) flat (i.e., non-hierarchical) reservation
+ * environment.
+ */
+struct sup_reservation_environment {
+        struct reservation_environment env;
+
+        /* ordered by priority */
+        struct list_head active_reservations;
+
+        /* ordered by next_replenishment */
+        struct list_head depleted_reservations;
+
+        /* unordered */
+        struct list_head inactive_reservations;
+
+        /* - SUP_RESCHEDULE_NOW means call sup_dispatch() now
+         * - SUP_NO_SCHEDULER_UPDATE means nothing to do
+         * any other value means program a timer for the given time
+         */
+        lt_t next_scheduler_update;
+        /* set to true if a call to sup_dispatch() is imminent */
+        bool will_schedule;
+};
+
+/* Contract:
+ *  - before calling into sup_ code, or any reservation methods,
+ *    update the time with sup_update_time(); and
+ *  - after calling into sup_ code, or any reservation methods,
+ *    check next_scheduler_update and program timer or trigger
+ *    scheduler invocation accordingly.
+ */
+
+void sup_init(struct sup_reservation_environment* sup_env);
+void sup_add_new_reservation(struct sup_reservation_environment* sup_env,
+        struct reservation* new_res);
+void sup_update_time(struct sup_reservation_environment* sup_env, lt_t now);
+struct task_struct* sup_dispatch(struct sup_reservation_environment* sup_env);
+
+struct reservation* sup_find_by_id(struct sup_reservation_environment* sup_env,
+        unsigned int id);
+
+#endif