[ported from 2008.3] Core LITMUS^RT infrastructure

Port 2008.3 Core LITMUS^RT infrastructure to Linux 2.6.32

litmus_sched_class implements 4 new methods:

- prio_changed:
  void

- switched_to:
  void

- get_rr_interval:
  return infinity (i.e., 0)

- select_task_rq:
  return current cpu

1 files changed, 175 insertions, 0 deletions

diff --git a/include/litmus/rt_param.h b/include/litmus/rt_param.h
new file mode 100644
index 000000000000..c599f848d1ed
--- /dev/null
+++ b/include/litmus/rt_param.h
@@ -0,0 +1,175 @@
+/*
+ * Definition of the scheduler plugin interface.
+ *
+ */
+#ifndef _LINUX_RT_PARAM_H_
+#define _LINUX_RT_PARAM_H_
+
+/* Litmus time type. */
+typedef unsigned long long lt_t;
+
+static inline int lt_after(lt_t a, lt_t b)
+{
+        return ((long long) b) - ((long long) a) < 0;
+}
+#define lt_before(a, b) lt_after(b, a)
+
+static inline int lt_after_eq(lt_t a, lt_t b)
+{
+        return ((long long) a) - ((long long) b) >= 0;
+}
+#define lt_before_eq(a, b) lt_after_eq(b, a)
+
+/* different types of clients */
+typedef enum {
+        RT_CLASS_HARD,
+        RT_CLASS_SOFT,
+        RT_CLASS_BEST_EFFORT
+} task_class_t;
+
+struct rt_task {
+        lt_t            exec_cost;
+        lt_t            period;
+        lt_t            phase;
+        unsigned int    cpu;
+        task_class_t    cls;
+};
+
+/* don't export internal data structures to user space (liblitmus) */
+#ifdef __KERNEL__
+
+struct _rt_domain;
+struct heap_node;
+struct release_heap;
+
+struct rt_job {
+        /* Time instant the the job was or will be released.  */
+        lt_t    release;
+        /* What is the current deadline? */
+        lt_t    deadline;
+
+        /* How much service has this job received so far? */
+        lt_t    exec_time;
+
+        /* Which job is this. This is used to let user space
+         * specify which job to wait for, which is important if jobs
+         * overrun. If we just call sys_sleep_next_period() then we
+         * will unintentionally miss jobs after an overrun.
+         *
+         * Increase this sequence number when a job is released.
+         */
+        unsigned int    job_no;
+};
+
+
+struct pfair_param;
+
+/*      RT task parameters for scheduling extensions
+ *      These parameters are inherited during clone and therefore must
+ *      be explicitly set up before the task set is launched.
+ */
+struct rt_param {
+        /* is the task sleeping? */
+        unsigned int            flags:8;
+
+        /* do we need to check for srp blocking? */
+        unsigned int            srp_non_recurse:1;
+
+        /* is the task present? (true if it can be scheduled) */
+        unsigned int            present:1;
+
+        /* user controlled parameters */
+        struct rt_task          task_params;
+
+        /* timing parameters */
+        struct rt_job           job_params;
+
+        /* task representing the current "inherited" task
+         * priority, assigned by inherit_priority and
+         * return priority in the scheduler plugins.
+         * could point to self if PI does not result in
+         * an increased task priority.
+         */
+         struct task_struct*    inh_task;
+
+        /* Don't just dereference this pointer in kernel space!
+         * It might very well point to junk or nothing at all.
+         * NULL indicates that the task has not requested any non-preemptable
+         * section support.
+         * Not inherited upon fork.
+         */
+        short*                  np_flag;
+
+        /* re-use unused counter in plugins that don't need it */
+        union {
+                /* For the FMLP under PSN-EDF, it is required to make the task
+                 * non-preemptive from kernel space. In order not to interfere with
+                 * user space, this counter indicates the kernel space np setting.
+                 * kernel_np > 0 => task is non-preemptive
+                 */
+                unsigned int    kernel_np;
+
+                /* Used by GQ-EDF */
+                unsigned int    last_cpu;
+        };
+
+        /* This field can be used by plugins to store where the task
+         * is currently scheduled. It is the responsibility of the
+         * plugin to avoid race conditions.
+         *
+         * This used by GSN-EDF and PFAIR.
+         */
+        volatile int            scheduled_on;
+
+        /* Is the stack of the task currently in use? This is updated by
+         * the LITMUS core.
+         *
+         * Be careful to avoid deadlocks!
+         */
+        volatile int            stack_in_use;
+
+        /* This field can be used by plugins to store where the task
+         * is currently linked. It is the responsibility of the plugin
+         * to avoid race conditions.
+         *
+         * Used by GSN-EDF.
+         */
+        volatile int            linked_on;
+
+        /* PFAIR/PD^2 state. Allocated on demand. */
+        struct pfair_param*     pfair;
+
+        /* Fields saved before BE->RT transition.
+         */
+        int old_policy;
+        int old_prio;
+
+        /* ready queue for this task */
+        struct _rt_domain* domain;
+
+        /* heap element for this task
+         *
+         * Warning: Don't statically allocate this node. The heap
+         *          implementation swaps these between tasks, thus after
+         *          dequeuing from a heap you may end up with a different node
+         *          then the one you had when enqueuing the task.  For the same
+         *          reason, don't obtain and store references to this node
+         *          other than this pointer (which is updated by the heap
+         *          implementation).
+         */
+        struct heap_node*       heap_node;
+        struct release_heap*    rel_heap;
+
+        /* Used by rt_domain to queue task in release list.
+         */
+        struct list_head list;
+};
+
+/*      Possible RT flags       */
+#define RT_F_RUNNING            0x00000000
+#define RT_F_SLEEP              0x00000001
+#define RT_F_EXIT_SEM           0x00000008
+
+#endif
+
+#endif