[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

10 files changed, 1038 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75e6e60bf583..bb046c0adf99 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -38,6 +38,7 @@
 #define SCHED_BATCH             3
 /* SCHED_ISO: reserved but not implemented yet */
 #define SCHED_IDLE              5
+#define SCHED_LITMUS            6
 /* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */
 #define SCHED_RESET_ON_FORK     0x40000000
 
@@ -94,6 +95,8 @@ struct sched_param {
 
 #include <asm/processor.h>
 
+#include <litmus/rt_param.h>
+
 struct exec_domain;
 struct futex_pi_state;
 struct robust_list_head;
@@ -1505,6 +1508,10 @@ struct task_struct {
         int make_it_fail;
 #endif
         struct prop_local_single dirties;
+
+        /* LITMUS RT parameters and state */
+        struct rt_param rt_param;
+
 #ifdef CONFIG_LATENCYTOP
         int latency_record_count;
         struct latency_record latency_record[LT_SAVECOUNT];
diff --git a/include/litmus/feather_buffer.h b/include/litmus/feather_buffer.h
new file mode 100644
index 000000000000..6c18277fdfc9
--- /dev/null
+++ b/include/litmus/feather_buffer.h
@@ -0,0 +1,94 @@
+#ifndef _FEATHER_BUFFER_H_
+#define _FEATHER_BUFFER_H_
+
+/* requires UINT_MAX and memcpy */
+
+#define SLOT_FREE       0
+#define SLOT_BUSY       1
+#define SLOT_READY      2
+
+struct ft_buffer {
+        unsigned int    slot_count;
+        unsigned int    slot_size;
+
+        int             free_count;
+        unsigned int    write_idx;
+        unsigned int    read_idx;
+
+        char*           slots;
+        void*           buffer_mem;
+        unsigned int    failed_writes;
+};
+
+static inline int init_ft_buffer(struct ft_buffer*      buf,
+                                 unsigned int           slot_count,
+                                 unsigned int           slot_size,
+                                 char*                  slots,
+                                 void*                  buffer_mem)
+{
+        int i = 0;
+        if (!slot_count || UINT_MAX % slot_count != slot_count - 1) {
+                /* The slot count must divide UNIT_MAX + 1 so that when it
+                 * wraps around the index correctly points to 0.
+                 */
+                return 0;
+        } else {
+                buf->slot_count    = slot_count;
+                buf->slot_size     = slot_size;
+                buf->slots         = slots;
+                buf->buffer_mem    = buffer_mem;
+                buf->free_count    = slot_count;
+                buf->write_idx     = 0;
+                buf->read_idx      = 0;
+                buf->failed_writes = 0;
+                for (i = 0; i < slot_count; i++)
+                        buf->slots[i] = SLOT_FREE;
+                return 1;
+        }
+}
+
+static inline int ft_buffer_start_write(struct ft_buffer* buf, void **ptr)
+{
+        int free = fetch_and_dec(&buf->free_count);
+        unsigned int idx;
+        if (free <= 0) {
+                fetch_and_inc(&buf->free_count);
+                *ptr = 0;
+                fetch_and_inc(&buf->failed_writes);
+                return 0;
+        } else {
+                idx  = fetch_and_inc((int*) &buf->write_idx) % buf->slot_count;
+                buf->slots[idx] = SLOT_BUSY;
+                *ptr = ((char*) buf->buffer_mem) + idx * buf->slot_size;
+                return 1;
+        }
+}
+
+static inline void ft_buffer_finish_write(struct ft_buffer* buf, void *ptr)
+{
+        unsigned int idx = ((char*) ptr - (char*) buf->buffer_mem) / buf->slot_size;
+        buf->slots[idx]  = SLOT_READY;
+}
+
+
+/* exclusive reader access is assumed */
+static inline int ft_buffer_read(struct ft_buffer* buf, void* dest)
+{
+        unsigned int idx;
+        if (buf->free_count == buf->slot_count)
+                /* nothing available */
+                return 0;
+        idx = buf->read_idx % buf->slot_count;
+        if (buf->slots[idx] == SLOT_READY) {
+                memcpy(dest, ((char*) buf->buffer_mem) + idx * buf->slot_size,
+                       buf->slot_size);
+                buf->slots[idx] = SLOT_FREE;
+                buf->read_idx++;
+                fetch_and_inc(&buf->free_count);
+                return 1;
+        } else
+                return 0;
+}
+
+
+#endif
diff --git a/include/litmus/feather_trace.h b/include/litmus/feather_trace.h
new file mode 100644
index 000000000000..3ac1ee5e0277
--- /dev/null
+++ b/include/litmus/feather_trace.h
@@ -0,0 +1,36 @@
+#ifndef _FEATHER_TRACE_H_
+#define _FEATHER_TRACE_H_
+
+
+int ft_enable_event(unsigned long id);
+int ft_disable_event(unsigned long id);
+int ft_is_event_enabled(unsigned long id);
+int ft_disable_all_events(void);
+
+#ifndef __ARCH_HAS_FEATHER_TRACE
+/* provide default implementation */
+
+#define feather_callback
+
+#define MAX_EVENTS 1024
+
+extern int ft_events[MAX_EVENTS];
+
+#define ft_event(id, callback) \
+        if (ft_events[id]) callback();
+
+#define ft_event0(id, callback) \
+        if (ft_events[id]) callback(id);
+
+#define ft_event1(id, callback, param) \
+        if (ft_events[id]) callback(id, param);
+
+#define ft_event2(id, callback, param, param2) \
+        if (ft_events[id]) callback(id, param, param2);
+
+#define ft_event3(id, callback, p, p2, p3) \
+        if (ft_events[id]) callback(id, p, p2, p3);
+#endif
+
+
+#endif
diff --git a/include/litmus/heap.h b/include/litmus/heap.h
new file mode 100644
index 000000000000..da959b0bec9c
--- /dev/null
+++ b/include/litmus/heap.h
@@ -0,0 +1,77 @@
+/* heaps.h -- Binomial Heaps
+ *
+ * (c) 2008, 2009 Bjoern Brandenburg
+ */
+
+#ifndef HEAP_H
+#define HEAP_H
+
+#define NOT_IN_HEAP UINT_MAX
+
+struct heap_node {
+        struct heap_node*       parent;
+        struct heap_node*       next;
+        struct heap_node*       child;
+
+        unsigned int            degree;
+        void*                   value;
+        struct heap_node**      ref;
+};
+
+struct heap {
+        struct heap_node*       head;
+        /* We cache the minimum of the heap.
+         * This speeds up repeated peek operations.
+         */
+        struct heap_node*       min;
+};
+
+typedef int (*heap_prio_t)(struct heap_node* a, struct heap_node* b);
+
+void heap_init(struct heap* heap);
+void heap_node_init(struct heap_node** ref_to_heap_node_ptr, void* value);
+
+static inline int heap_node_in_heap(struct heap_node* h)
+{
+        return h->degree != NOT_IN_HEAP;
+}
+
+static inline int heap_empty(struct heap* heap)
+{
+        return heap->head == NULL && heap->min == NULL;
+}
+
+/* insert (and reinitialize) a node into the heap */
+void heap_insert(heap_prio_t higher_prio,
+                 struct heap* heap,
+                 struct heap_node* node);
+
+/* merge addition into target */
+void heap_union(heap_prio_t higher_prio,
+                struct heap* target,
+                struct heap* addition);
+
+struct heap_node* heap_peek(heap_prio_t higher_prio,
+                            struct heap* heap);
+
+struct heap_node* heap_take(heap_prio_t higher_prio,
+                            struct heap* heap);
+
+void heap_uncache_min(heap_prio_t higher_prio, struct heap* heap);
+int  heap_decrease(heap_prio_t higher_prio, struct heap_node* node);
+
+void heap_delete(heap_prio_t higher_prio,
+                 struct heap* heap,
+                 struct heap_node* node);
+
+/* allocate from memcache */
+struct heap_node* heap_node_alloc(int gfp_flags);
+void heap_node_free(struct heap_node* hn);
+
+/* allocate a heap node for value and insert into the heap */
+int heap_add(heap_prio_t higher_prio, struct heap* heap,
+             void* value, int gfp_flags);
+
+void* heap_take_del(heap_prio_t higher_prio,
+                    struct heap* heap);
+#endif
diff --git a/include/litmus/jobs.h b/include/litmus/jobs.h
new file mode 100644
index 000000000000..9bd361ef3943
--- /dev/null
+++ b/include/litmus/jobs.h
@@ -0,0 +1,9 @@
+#ifndef __LITMUS_JOBS_H__
+#define __LITMUS_JOBS_H__
+
+void prepare_for_next_period(struct task_struct *t);
+void release_at(struct task_struct *t, lt_t start);
+long complete_job(void);
+
+#endif
+
diff --git a/include/litmus/litmus.h b/include/litmus/litmus.h
new file mode 100644
index 000000000000..380fcb8acb33
--- /dev/null
+++ b/include/litmus/litmus.h
@@ -0,0 +1,177 @@
+/*
+ * Constant definitions related to
+ * scheduling policy.
+ */
+
+#ifndef _LINUX_LITMUS_H_
+#define _LINUX_LITMUS_H_
+
+#include <linux/jiffies.h>
+#include <litmus/sched_trace.h>
+
+extern atomic_t release_master_cpu;
+
+extern atomic_t __log_seq_no;
+
+#define TRACE(fmt, args...) \
+        sched_trace_log_message("%d P%d: " fmt, atomic_add_return(1, &__log_seq_no), \
+                                raw_smp_processor_id(), ## args)
+
+#define TRACE_TASK(t, fmt, args...) \
+        TRACE("(%s/%d) " fmt, (t)->comm, (t)->pid, ##args)
+
+#define TRACE_CUR(fmt, args...) \
+        TRACE_TASK(current, fmt, ## args)
+
+#define TRACE_BUG_ON(cond) \
+        do { if (cond) TRACE("BUG_ON(%s) at %s:%d " \
+                             "called from %p current=%s/%d state=%d " \
+                             "flags=%x partition=%d cpu=%d rtflags=%d"\
+                             " job=%u knp=%d timeslice=%u\n",           \
+        #cond, __FILE__, __LINE__, __builtin_return_address(0), current->comm, \
+        current->pid, current->state, current->flags,  \
+        get_partition(current), smp_processor_id(), get_rt_flags(current), \
+        current->rt_param.job_params.job_no, current->rt_param.kernel_np, \
+        current->rt.time_slice\
+        ); } while(0);
+
+
+/* in_list - is a given list_head queued on some list?
+ */
+static inline int in_list(struct list_head* list)
+{
+        return !(  /* case 1: deleted */
+                   (list->next == LIST_POISON1 &&
+                    list->prev == LIST_POISON2)
+                 ||
+                   /* case 2: initialized */
+                   (list->next == list &&
+                    list->prev == list)
+                );
+}
+
+#define NO_CPU                  0xffffffff
+
+void litmus_fork(struct task_struct *tsk);
+void litmus_exec(void);
+/* clean up real-time state of a task */
+void exit_litmus(struct task_struct *dead_tsk);
+
+long litmus_admit_task(struct task_struct *tsk);
+void litmus_exit_task(struct task_struct *tsk);
+
+#define is_realtime(t)          ((t)->policy == SCHED_LITMUS)
+#define rt_transition_pending(t) \
+        ((t)->rt_param.transition_pending)
+
+#define tsk_rt(t)               (&(t)->rt_param)
+
+/*      Realtime utility macros */
+#define get_rt_flags(t)         (tsk_rt(t)->flags)
+#define set_rt_flags(t,f)       (tsk_rt(t)->flags=(f))
+#define get_exec_cost(t)        (tsk_rt(t)->task_params.exec_cost)
+#define get_exec_time(t)        (tsk_rt(t)->job_params.exec_time)
+#define get_rt_period(t)        (tsk_rt(t)->task_params.period)
+#define get_rt_phase(t)         (tsk_rt(t)->task_params.phase)
+#define get_partition(t)        (tsk_rt(t)->task_params.cpu)
+#define get_deadline(t)         (tsk_rt(t)->job_params.deadline)
+#define get_release(t)          (tsk_rt(t)->job_params.release)
+#define get_class(t)            (tsk_rt(t)->task_params.cls)
+
+inline static int budget_exhausted(struct task_struct* t)
+{
+        return get_exec_time(t) >= get_exec_cost(t);
+}
+
+
+#define is_hrt(t)               \
+        (tsk_rt(t)->task_params.class == RT_CLASS_HARD)
+#define is_srt(t)               \
+        (tsk_rt(t)->task_params.class == RT_CLASS_SOFT)
+#define is_be(t)                \
+        (tsk_rt(t)->task_params.class == RT_CLASS_BEST_EFFORT)
+
+/* Our notion of time within LITMUS: kernel monotonic time. */
+static inline lt_t litmus_clock(void)
+{
+        return ktime_to_ns(ktime_get());
+}
+
+/* A macro to convert from nanoseconds to ktime_t. */
+#define ns_to_ktime(t)          ktime_add_ns(ktime_set(0, 0), t)
+
+#define get_domain(t) (tsk_rt(t)->domain)
+
+/* Honor the flag in the preempt_count variable that is set
+ * when scheduling is in progress.
+ */
+#define is_running(t)                   \
+        ((t)->state == TASK_RUNNING ||  \
+         task_thread_info(t)->preempt_count & PREEMPT_ACTIVE)
+
+#define is_blocked(t)       \
+        (!is_running(t))
+#define is_released(t, now)     \
+        (lt_before_eq(get_release(t), now))
+#define is_tardy(t, now)    \
+        (lt_before_eq(tsk_rt(t)->job_params.deadline, now))
+
+/* real-time comparison macros */
+#define earlier_deadline(a, b) (lt_before(\
+        (a)->rt_param.job_params.deadline,\
+        (b)->rt_param.job_params.deadline))
+#define earlier_release(a, b)  (lt_before(\
+        (a)->rt_param.job_params.release,\
+        (b)->rt_param.job_params.release))
+
+#define make_np(t) do {t->rt_param.kernel_np++;} while(0);
+#define take_np(t) do {t->rt_param.kernel_np--;} while(0);
+
+#ifdef CONFIG_SRP
+void srp_ceiling_block(void);
+#else
+#define srp_ceiling_block() /* nothing */
+#endif
+
+#define heap2task(hn) ((struct task_struct*) hn->value)
+
+static inline int is_np(struct task_struct *t)
+{
+        return tsk_rt(t)->kernel_np;
+}
+
+#define  request_exit_np(t)
+
+static inline int is_present(struct task_struct* t)
+{
+        return t && tsk_rt(t)->present;
+}
+
+
+/* make the unit explicit */
+typedef unsigned long quanta_t;
+
+enum round {
+        FLOOR,
+        CEIL
+};
+
+
+/* Tick period is used to convert ns-specified execution
+ * costs and periods into tick-based equivalents.
+ */
+extern ktime_t tick_period;
+
+static inline quanta_t time2quanta(lt_t time, enum round round)
+{
+        s64  quantum_length = ktime_to_ns(tick_period);
+
+        if (do_div(time, quantum_length) && round == CEIL)
+                time++;
+        return (quanta_t) time;
+}
+
+/* By how much is cpu staggered behind CPU 0? */
+u64 cpu_stagger_offset(int cpu);
+
+#endif
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
diff --git a/include/litmus/sched_plugin.h b/include/litmus/sched_plugin.h
new file mode 100644
index 000000000000..94952f6ccbfa
--- /dev/null
+++ b/include/litmus/sched_plugin.h
@@ -0,0 +1,159 @@
+/*
+ * Definition of the scheduler plugin interface.
+ *
+ */
+#ifndef _LINUX_SCHED_PLUGIN_H_
+#define _LINUX_SCHED_PLUGIN_H_
+
+#include <linux/sched.h>
+
+/* struct for semaphore with priority inheritance */
+struct pi_semaphore {
+        atomic_t count;
+        int sleepers;
+        wait_queue_head_t wait;
+        union {
+                /* highest-prio holder/waiter */
+                struct task_struct *task;
+                struct task_struct* cpu_task[NR_CPUS];
+        } hp;
+        /* current lock holder */
+        struct task_struct *holder;
+};
+
+/************************ setup/tear down ********************/
+
+typedef long (*activate_plugin_t) (void);
+typedef long (*deactivate_plugin_t) (void);
+
+
+
+/********************* scheduler invocation ******************/
+
+/*  Plugin-specific realtime tick handler */
+typedef void (*scheduler_tick_t) (struct task_struct *cur);
+/* Novell make sched decision function */
+typedef struct task_struct* (*schedule_t)(struct task_struct * prev);
+/* Clean up after the task switch has occured.
+ * This function is called after every (even non-rt) task switch.
+ */
+typedef void (*finish_switch_t)(struct task_struct *prev);
+
+
+/********************* task state changes ********************/
+
+/* Called to setup a new real-time task.
+ * Release the first job, enqueue, etc.
+ * Task may already be running.
+ */
+typedef void (*task_new_t) (struct task_struct *task,
+                            int on_rq,
+                            int running);
+
+/* Called to re-introduce a task after blocking.
+ * Can potentially be called multiple times.
+ */
+typedef void (*task_wake_up_t) (struct task_struct *task);
+/* called to notify the plugin of a blocking real-time task
+ * it will only be called for real-time tasks and before schedule is called */
+typedef void (*task_block_t)  (struct task_struct *task);
+/* Called when a real-time task exits or changes to a different scheduling
+ * class.
+ * Free any allocated resources
+ */
+typedef void (*task_exit_t)    (struct task_struct *);
+
+/* Called when the new_owner is released from the wait queue
+ * it should now inherit the priority from sem, _before_ it gets readded
+ * to any queue
+ */
+typedef long (*inherit_priority_t) (struct pi_semaphore *sem,
+                                    struct task_struct *new_owner);
+
+/* Called when the current task releases a semahpore where it might have
+ * inherited a piority from
+ */
+typedef long (*return_priority_t) (struct pi_semaphore *sem);
+
+/* Called when a task tries to acquire a semaphore and fails. Check if its
+ * priority is higher than that of the current holder.
+ */
+typedef long (*pi_block_t) (struct pi_semaphore *sem, struct task_struct *t);
+
+
+
+
+/********************* sys call backends  ********************/
+/* This function causes the caller to sleep until the next release */
+typedef long (*complete_job_t) (void);
+
+typedef long (*admit_task_t)(struct task_struct* tsk);
+
+typedef void (*release_at_t)(struct task_struct *t, lt_t start);
+
+struct sched_plugin {
+        struct list_head        list;
+        /*      basic info              */
+        char                    *plugin_name;
+
+        /*      setup                   */
+        activate_plugin_t       activate_plugin;
+        deactivate_plugin_t     deactivate_plugin;
+
+#ifdef CONFIG_SRP
+        unsigned int            srp_active;
+#endif
+
+        /*      scheduler invocation    */
+        scheduler_tick_t        tick;
+        schedule_t              schedule;
+        finish_switch_t         finish_switch;
+
+        /*      syscall backend         */
+        complete_job_t          complete_job;
+        release_at_t            release_at;
+
+        /*      task state changes      */
+        admit_task_t            admit_task;
+
+        task_new_t              task_new;
+        task_wake_up_t          task_wake_up;
+        task_block_t            task_block;
+        task_exit_t             task_exit;
+
+#ifdef CONFIG_FMLP
+        /*     priority inheritance     */
+        unsigned int            fmlp_active;
+        inherit_priority_t      inherit_priority;
+        return_priority_t       return_priority;
+        pi_block_t              pi_block;
+#endif
+} __attribute__ ((__aligned__(SMP_CACHE_BYTES)));
+
+
+extern struct sched_plugin *litmus;
+
+int register_sched_plugin(struct sched_plugin* plugin);
+struct sched_plugin* find_sched_plugin(const char* name);
+int print_sched_plugins(char* buf, int max);
+
+static inline int srp_active(void)
+{
+#ifdef CONFIG_SRP
+        return litmus->srp_active;
+#else
+        return 0;
+#endif
+}
+static inline int fmlp_active(void)
+{
+#ifdef CONFIG_FMLP
+        return litmus->fmlp_active;
+#else
+        return 0;
+#endif
+}
+
+extern struct sched_plugin linux_sched_plugin;
+
+#endif
diff --git a/include/litmus/sched_trace.h b/include/litmus/sched_trace.h
new file mode 100644
index 000000000000..afd0391d127b
--- /dev/null
+++ b/include/litmus/sched_trace.h
@@ -0,0 +1,191 @@
+/* sched_trace.h -- record scheduler events to a byte stream for offline analysis.
+ */
+#ifndef _LINUX_SCHED_TRACE_H_
+#define _LINUX_SCHED_TRACE_H_
+
+/* all times in nanoseconds */
+
+struct st_trace_header {
+        u8      type;           /* Of what type is this record?  */
+        u8      cpu;            /* On which CPU was it recorded? */
+        u16     pid;            /* PID of the task.              */
+        u32     job;            /* The job sequence number.      */
+};
+
+#define ST_NAME_LEN 16
+struct st_name_data {
+        char    cmd[ST_NAME_LEN];/* The name of the executable of this process. */
+};
+
+struct st_param_data {          /* regular params */
+        u32     wcet;
+        u32     period;
+        u32     phase;
+        u8      partition;
+        u8      __unused[3];
+};
+
+struct st_release_data {        /* A job is was/is going to be released. */
+        u64     release;        /* What's the release time?              */
+        u64     deadline;       /* By when must it finish?               */
+};
+
+struct st_assigned_data {       /* A job was asigned to a CPU.           */
+        u64     when;
+        u8      target;         /* Where should it execute?              */
+        u8      __unused[3];
+};
+
+struct st_switch_to_data {      /* A process was switched to on a given CPU.   */
+        u64     when;           /* When did this occur?                        */
+        u32     exec_time;      /* Time the current job has executed.          */
+
+};
+
+struct st_switch_away_data {    /* A process was switched away from on a given CPU. */
+        u64     when;
+        u64     exec_time;
+};
+
+struct st_completion_data {     /* A job completed. */
+        u64     when;
+        u8      forced:1;       /* Set to 1 if job overran and kernel advanced to the
+                                 * next task automatically; set to 0 otherwise.
+                                 */
+        u8      __uflags:7;
+        u8      __unused[3];
+};
+
+struct st_block_data {          /* A task blocks. */
+        u64     when;
+        u64     __unused;
+};
+
+struct st_resume_data {         /* A task resumes. */
+        u64     when;
+        u64     __unused;
+};
+
+struct st_sys_release_data {
+        u64     when;
+        u64     release;
+};
+
+#define DATA(x) struct st_ ## x ## _data x;
+
+typedef enum {
+        ST_NAME = 1,            /* Start at one, so that we can spot
+                                 * uninitialized records. */
+        ST_PARAM,
+        ST_RELEASE,
+        ST_ASSIGNED,
+        ST_SWITCH_TO,
+        ST_SWITCH_AWAY,
+        ST_COMPLETION,
+        ST_BLOCK,
+        ST_RESUME,
+        ST_SYS_RELEASE,
+} st_event_record_type_t;
+
+struct st_event_record {
+        struct st_trace_header hdr;
+        union {
+                u64 raw[2];
+
+                DATA(name);
+                DATA(param);
+                DATA(release);
+                DATA(assigned);
+                DATA(switch_to);
+                DATA(switch_away);
+                DATA(completion);
+                DATA(block);
+                DATA(resume);
+                DATA(sys_release);
+
+        } data;
+};
+
+#undef DATA
+
+#ifdef __KERNEL__
+
+#include <linux/sched.h>
+#include <litmus/feather_trace.h>
+
+#ifdef CONFIG_SCHED_TASK_TRACE
+
+#define SCHED_TRACE(id, callback, task) \
+        ft_event1(id, callback, task)
+#define SCHED_TRACE2(id, callback, task, xtra) \
+        ft_event2(id, callback, task, xtra)
+
+/* provide prototypes; needed on sparc64 */
+#ifndef NO_TASK_TRACE_DECLS
+feather_callback void do_sched_trace_task_name(unsigned long id,
+                                               struct task_struct* task);
+feather_callback void do_sched_trace_task_param(unsigned long id,
+                                                struct task_struct* task);
+feather_callback void do_sched_trace_task_release(unsigned long id,
+                                                  struct task_struct* task);
+feather_callback void do_sched_trace_task_switch_to(unsigned long id,
+                                                    struct task_struct* task);
+feather_callback void do_sched_trace_task_switch_away(unsigned long id,
+                                                      struct task_struct* task);
+feather_callback void do_sched_trace_task_completion(unsigned long id,
+                                                     struct task_struct* task,
+                                                     unsigned long forced);
+feather_callback void do_sched_trace_task_block(unsigned long id,
+                                                struct task_struct* task);
+feather_callback void do_sched_trace_task_resume(unsigned long id,
+                                                 struct task_struct* task);
+feather_callback void do_sched_trace_sys_release(unsigned long id,
+                                                 lt_t* start);
+#endif
+
+#else
+
+#define SCHED_TRACE(id, callback, task)        /* no tracing */
+#define SCHED_TRACE2(id, callback, task, xtra) /* no tracing */
+
+#endif
+
+
+#define SCHED_TRACE_BASE_ID 500
+
+
+#define sched_trace_task_name(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 1, do_sched_trace_task_name, t)
+#define sched_trace_task_param(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 2, do_sched_trace_task_param, t)
+#define sched_trace_task_release(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 3, do_sched_trace_task_release, t)
+#define sched_trace_task_switch_to(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 4, do_sched_trace_task_switch_to, t)
+#define sched_trace_task_switch_away(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 5, do_sched_trace_task_switch_away, t)
+#define sched_trace_task_completion(t, forced) \
+        SCHED_TRACE2(SCHED_TRACE_BASE_ID + 6, do_sched_trace_task_completion, t, \
+                     forced)
+#define sched_trace_task_block(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 7, do_sched_trace_task_block, t)
+#define sched_trace_task_resume(t) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 8, do_sched_trace_task_resume, t)
+
+#define sched_trace_sys_release(when) \
+        SCHED_TRACE(SCHED_TRACE_BASE_ID + 9, do_sched_trace_sys_release, when)
+
+#define sched_trace_quantum_boundary() /* NOT IMPLEMENTED */
+
+#ifdef CONFIG_SCHED_DEBUG_TRACE
+void sched_trace_log_message(const char* fmt, ...);
+void dump_trace_buffer(int max);
+#else
+
+#define sched_trace_log_message(fmt, ...)
+
+#endif
+
+#endif /* __KERNEL__ */
+
+#endif
diff --git a/include/litmus/trace.h b/include/litmus/trace.h
new file mode 100644
index 000000000000..e8e0c7b6cc6a
--- /dev/null
+++ b/include/litmus/trace.h
@@ -0,0 +1,113 @@
+#ifndef _SYS_TRACE_H_
+#define _SYS_TRACE_H_
+
+#ifdef CONFIG_SCHED_OVERHEAD_TRACE
+
+#include <litmus/feather_trace.h>
+#include <litmus/feather_buffer.h>
+
+
+/*********************** TIMESTAMPS ************************/
+
+enum task_type_marker {
+        TSK_BE,
+        TSK_RT,
+        TSK_UNKNOWN
+};
+
+struct timestamp {
+        uint64_t                timestamp;
+        uint32_t                seq_no;
+        uint8_t                 cpu;
+        uint8_t                 event;
+        uint8_t                 task_type;
+};
+
+/* tracing callbacks */
+feather_callback void save_timestamp(unsigned long event);
+feather_callback void save_timestamp_def(unsigned long event, unsigned long type);
+feather_callback void save_timestamp_task(unsigned long event, unsigned long t_ptr);
+feather_callback void save_timestamp_cpu(unsigned long event, unsigned long cpu);
+
+
+#define TIMESTAMP(id) ft_event0(id, save_timestamp)
+
+#define DTIMESTAMP(id, def)  ft_event1(id, save_timestamp_def, def)
+
+#define TTIMESTAMP(id, task) \
+        ft_event1(id, save_timestamp_task, (unsigned long) task)
+
+#define CTIMESTAMP(id, cpu) \
+        ft_event1(id, save_timestamp_cpu, cpu)
+
+#else /* !CONFIG_SCHED_OVERHEAD_TRACE */
+
+#define TIMESTAMP(id)        /* no tracing */
+
+#define DTIMESTAMP(id, def)  /* no tracing */
+
+#define TTIMESTAMP(id, task) /* no tracing */
+
+#define CTIMESTAMP(id, cpu)  /* no tracing */
+
+#endif
+
+
+/* Convention for timestamps
+ * =========================
+ *
+ * In order to process the trace files with a common tool, we use the following
+ * convention to measure execution times: The end time id of a code segment is
+ * always the next number after the start time event id.
+ */
+
+#define TS_SCHED_START                  DTIMESTAMP(100, TSK_UNKNOWN) /* we only
+                                                                      * care
+                                                                      * about
+                                                                      * next */
+#define TS_SCHED_END(t)                 TTIMESTAMP(101, t)
+#define TS_SCHED2_START(t)              TTIMESTAMP(102, t)
+#define TS_SCHED2_END(t)                TTIMESTAMP(103, t)
+
+#define TS_CXS_START(t)                 TTIMESTAMP(104, t)
+#define TS_CXS_END(t)                   TTIMESTAMP(105, t)
+
+#define TS_RELEASE_START                DTIMESTAMP(106, TSK_RT)
+#define TS_RELEASE_END                  DTIMESTAMP(107, TSK_RT)
+
+#define TS_TICK_START(t)                TTIMESTAMP(110, t)
+#define TS_TICK_END(t)                  TTIMESTAMP(111, t)
+
+
+#define TS_PLUGIN_SCHED_START           /* TIMESTAMP(120) */  /* currently unused */
+#define TS_PLUGIN_SCHED_END             /* TIMESTAMP(121) */
+
+#define TS_PLUGIN_TICK_START            /* TIMESTAMP(130) */
+#define TS_PLUGIN_TICK_END              /* TIMESTAMP(131) */
+
+#define TS_ENTER_NP_START               TIMESTAMP(140)
+#define TS_ENTER_NP_END                 TIMESTAMP(141)
+
+#define TS_EXIT_NP_START                TIMESTAMP(150)
+#define TS_EXIT_NP_END                  TIMESTAMP(151)
+
+#define TS_SRP_UP_START                 TIMESTAMP(160)
+#define TS_SRP_UP_END                   TIMESTAMP(161)
+#define TS_SRP_DOWN_START               TIMESTAMP(162)
+#define TS_SRP_DOWN_END                 TIMESTAMP(163)
+
+#define TS_PI_UP_START                  TIMESTAMP(170)
+#define TS_PI_UP_END                    TIMESTAMP(171)
+#define TS_PI_DOWN_START                TIMESTAMP(172)
+#define TS_PI_DOWN_END                  TIMESTAMP(173)
+
+#define TS_FIFO_UP_START                TIMESTAMP(180)
+#define TS_FIFO_UP_END                  TIMESTAMP(181)
+#define TS_FIFO_DOWN_START              TIMESTAMP(182)
+#define TS_FIFO_DOWN_END                TIMESTAMP(183)
+
+#define TS_SEND_RESCHED_START(c)        CTIMESTAMP(190, c)
+#define TS_SEND_RESCHED_END             DTIMESTAMP(191, TSK_UNKNOWN)
+
+
+#endif /* !_SYS_TRACE_H_ */