Generalizd architecture for GEDF-style scheduelrs to reduce code redundancy.wip-refactored-gedf

This patch hoists nearly all of the non-GEDF specific code (decision
making (GEDF) vs. carrying out decisions (non-specific)) out of
sched_gsn_edf.c and into a new generic sched_global_plugin architecture.
A new struct, sched_global_plugin, provides the needed hooks for other
GEDF-style schedulers to reuse the non-scheduler-specific code.

You may conceptualize this new architecture (in OO-terms) as:
* sched_plugin is the parent of sched_global_plugin.
* sched_global_plugin is the parent of gsn_edf_plugin.
* Both sched_plugin and sched_global_plugin are "pure virtual"

This patch drastically reduces the amount of code needed to support
G-EDF, EDZL, (Adaptive) EDZL, etc.

2 files changed, 100 insertions, 1 deletions

diff --git a/include/litmus/sched_global_plugin.h b/include/litmus/sched_global_plugin.h
new file mode 100644
index 000000000000..cac2de63a3ee
--- /dev/null
+++ b/include/litmus/sched_global_plugin.h
@@ -0,0 +1,99 @@
+#ifndef _LITMUS_SCHED_GLOBAL_PLUGIN_H_
+
+
+#include <linux/sched.h>
+
+#include <litmus/litmus.h>
+#include <litmus/sched_plugin.h>
+#include <litmus/rt_domain.h>
+#include <litmus/bheap.h>
+
+/* cpu_entry_t - maintain the linked and scheduled state
+ */
+typedef struct  {
+        int                     cpu;
+        struct task_struct*     linked;         /* only RT tasks */
+        struct task_struct*     scheduled;      /* only RT tasks */
+        struct bheap_node*      hn;
+} cpu_entry_t;
+
+
+/*
+ For use by G-EDF family of plugins (G-EDF, EDZL, etc.).
+ These plugins differ mainly by actual rt_domain_t and
+ priority-order comparator functions and a few hooks for
+ timers.
+ */
+typedef int (*prio_compare_t)(struct task_struct*, struct task_struct*);
+typedef struct task_struct* (*take_ready_t)(rt_domain_t* rt);
+typedef void (*add_ready_t)(rt_domain_t* rt, struct task_struct *new);
+typedef void (*job_arrival_t)(struct task_struct* task);
+typedef void (*job_completion_t)(struct task_struct *t, int forced);
+
+
+struct sched_global_plugin {
+    
+    struct sched_plugin plugin;
+    
+    /* function pointers MUST be set by plugin */
+    prio_compare_t  prio_order;
+    take_ready_t    take_ready;
+    add_ready_t     add_ready;
+    job_arrival_t   job_arrival;
+    job_completion_t    job_completion;
+    
+    rt_domain_t domain;
+    
+    cpu_entry_t* cpus[NR_CPUS];
+    struct bheap_node heap_node[NR_CPUS];
+    struct bheap      cpu_heap;
+    
+} __attribute__ ((__aligned__(SMP_CACHE_BYTES)));
+
+
+extern struct sched_global_plugin* active_gbl_plugin;
+
+
+/*
+ * "Member" functions for generic global scheduling.
+ * Will call down into "virtual" functions as needed.
+ *
+ * Use prefix "gbl_" (global)
+ */
+int gbl_preemption_needed(struct task_struct *t);
+int gbl_ready_order(struct bheap_node* a, struct bheap_node* b);
+int gbl_cpu_lower_prio(struct bheap_node *_a, struct bheap_node *_b);
+void gbl_update_cpu_position(cpu_entry_t *entry);
+cpu_entry_t* gbl_lowest_prio_cpu(void);
+void gbl_link_task_to_cpu(struct task_struct* linked, cpu_entry_t *entry);
+void gbl_unlink(struct task_struct* t);
+void gbl_preempt(cpu_entry_t *entry);
+void gbl_requeue(struct task_struct* task);
+void gbl_check_for_preemptions(void);
+void gbl_release_jobs(rt_domain_t* rt, struct bheap* tasks);
+void gbl_job_completion(struct task_struct *t, int forced);
+
+/* Think of these two functions as "static" member functions */
+void gbl_domain_init(struct sched_global_plugin* gbl_plugin,
+                     check_resched_needed_t resched,
+                     release_jobs_t release);
+long gbl_activate_plugin(void* plugin);
+
+
+/*
+ * "Virtual member" functions for generic global scheduling.
+ * For use with sched_plugin or sched_global_plugin.
+ *
+ * Use prefix "gblv_" (global virtual)
+ */
+void gblv_job_arrival(struct task_struct* task);
+void gblv_tick(struct task_struct* t);
+struct task_struct* gblv_schedule(struct task_struct * prev);
+void gblv_finish_switch(struct task_struct *prev);
+void gblv_task_new(struct task_struct * t, int on_rq, int running);
+void gblv_task_wake_up(struct task_struct *task);
+void gblv_task_block(struct task_struct *t);
+void gblv_task_exit(struct task_struct * t);
+long gblv_admit_task(struct task_struct* tsk);
+
+#endif
\ No newline at end of file
diff --git a/include/litmus/sched_plugin.h b/include/litmus/sched_plugin.h
index 2d856d587041..6899816ea321 100644
--- a/include/litmus/sched_plugin.h
+++ b/include/litmus/sched_plugin.h
@@ -23,7 +23,7 @@ struct pi_semaphore {
 
 /************************ setup/tear down ********************/
 
-typedef long (*activate_plugin_t) (void);
+typedef long (*activate_plugin_t) (void* plugin);
 typedef long (*deactivate_plugin_t) (void);