Add EDCL scheduler

simso/schedulers/EDCL.py

+#!/usr/bin/python
+# coding=utf-8
+__author__ = 'Pierre-Emmanuel Hladik'
+
+
+from simso.core import Scheduler
+
+
+class EDCL(Scheduler):
+    """
+    EDCL Scheduler.
+    Global EDF-based Scheduling with Efficient Priority Promotion.
+    Shinpei Kato and Nobuyuki Yamasaki.
+    The 14th International Conference on Embedded and Real-Time Computing
+    Systems and Applications, 2008
+    """
+    def on_activate(self, job):
+        job.cpu.resched()
+
+    def on_terminated(self, job):
+        job.cpu.resched()
+
+    def update_laxity(self):
+        for t in self.task_list:
+            if t.is_active():
+                job = t.job
+                laxity = (job.absolute_deadline - job.ret
+                          ) * self.sim.cycles_per_ms - self.sim.now()
+                # if laxity is less than 0, the job will never respect its deadline,
+                # so we do not consider this job as critical
+                if laxity == 0:
+                    job.data['priority'] = 0
+                else:
+                    job.data['priority'] = job.absolute_deadline
+
+    def schedule(self, cpu):
+        self.update_laxity()
+        # List of ready jobs not currently running:
+        ready_jobs = [t.job for t in self.task_list
+                      if t.is_active() and not t.job.is_running()]
+
+        if ready_jobs:
+            # Select a free processor or, if none,
+            # the one with the greatest deadline (self in case of equality):
+            key = lambda x: (
+                1 if not x.running else 0,
+                x.running.absolute_deadline if x.running else 0,
+                1 if x is cpu else 0
+            )
+            cpu_min = max(self.processors, key=key)
+
+            # Select the job with the least priority:
+            job = min(ready_jobs, key=lambda x: x.data['priority'])
+
+            if (cpu_min.running is None or
+                    cpu_min.running.absolute_deadline > job.absolute_deadline):
+                return (job, cpu_min)
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