From 83057ba7c2d4916e54c71efe80f086adfab08f13 Mon Sep 17 00:00:00 2001
From: Glenn Elliott <gelliott@cs.unc.edu>
Date: Fri, 27 Sep 2013 13:19:57 -0400
Subject: PGM release/deadline adjustment.

Adds code that adjusts a jobs release and deadline
according to when the job receives the necessary
PGM tokens.
---
 include/litmus/pgm.h | 11 +++++++++++
 litmus/Makefile      |  1 +
 litmus/pgm.c         | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+)
 create mode 100644 include/litmus/pgm.h
 create mode 100644 litmus/pgm.c

diff --git a/include/litmus/pgm.h b/include/litmus/pgm.h
new file mode 100644
index 000000000000..1e87e170e8c3
--- /dev/null
+++ b/include/litmus/pgm.h
@@ -0,0 +1,11 @@
+#ifndef _LITMUS_PGM_H_
+#define _LITMUS_PGM_H_
+
+#include <litmus/litmus.h>
+
+#define is_pgm_waiting(t) (tsk_rt(t)->ctrl_page && tsk_rt(t)->ctrl_page->pgm_waiting)
+#define is_pgm_satisfied(t) (tsk_rt(t)->ctrl_page && tsk_rt(t)->ctrl_page->pgm_satisfied)
+
+void setup_pgm_release(struct task_struct* t);
+
+#endif
diff --git a/litmus/Makefile b/litmus/Makefile
index 2bddc94a399f..52f407cad77c 100644
--- a/litmus/Makefile
+++ b/litmus/Makefile
@@ -26,6 +26,7 @@ obj-y     = sched_plugin.o litmus.o \
 obj-$(CONFIG_PLUGIN_CEDF) += sched_cedf.o
 obj-$(CONFIG_PLUGIN_PFAIR) += sched_pfair.o
 obj-$(CONFIG_SCHED_CPU_AFFINITY) += affinity.o
+obj-$(CONFIG_SCHED_PGM) += pgm.o
 
 obj-$(CONFIG_FEATHER_TRACE) += ft_event.o ftdev.o
 obj-$(CONFIG_SCHED_TASK_TRACE) += sched_task_trace.o
diff --git a/litmus/pgm.c b/litmus/pgm.c
new file mode 100644
index 000000000000..f8b857de8118
--- /dev/null
+++ b/litmus/pgm.c
@@ -0,0 +1,54 @@
+/* litmus/pgm.c - common pgm control code
+ */
+
+#include <linux/sched.h>
+#include <litmus/litmus.h>
+#include <litmus/pgm.h>
+
+/* Only readjust release/deadline if difference is over a given threshold.
+   It's a weak method for accounting overheads. Ideally, we'd know the last
+   time t was woken up by its last predecessor, rather than having to look
+   at 'now'. */
+#define ADJUSTMENT_THRESH_US 200
+
+void setup_pgm_release(struct task_struct* t)
+{
+	/* approximate time last predecessor gave us tokens */
+	lt_t now = litmus_clock();
+
+	TRACE_TASK(t, "is starting a new PGM job: waiting:%d  satisfied:%d\n",
+		tsk_rt(t)->ctrl_page->pgm_waiting, tsk_rt(t)->ctrl_page->pgm_satisfied);
+
+	BUG_ON(!tsk_rt(t)->ctrl_page->pgm_waiting || !tsk_rt(t)->ctrl_page->pgm_satisfied);
+
+	tsk_rt(t)->ctrl_page->pgm_waiting = 0;
+	tsk_rt(t)->ctrl_page->pgm_satisfied = 0;
+
+	/* Adjust release time if we got the last tokens after release of this job.
+	   This is possible since PGM jobs are early-released. Don't shift our
+	   deadline if we got the tokens earlier than expected. */
+	if (now > tsk_rt(t)->job_params.release) {
+		long long diff = now - tsk_rt(t)->job_params.release;
+		if (diff > ADJUSTMENT_THRESH_US) {
+			lt_t adj_deadline = now + get_rt_relative_deadline(t);
+
+			TRACE_TASK(t, "adjusting PGM release time from (r = %llu, d = %llu) "
+				"to (r = %llu, d = %llu)\n",
+				tsk_rt(t)->job_params.release, tsk_rt(t)->job_params.deadline,
+				now, adj_deadline);
+
+			tsk_rt(t)->job_params.release = now;
+			tsk_rt(t)->job_params.deadline = adj_deadline;
+			tsk_rt(t)->job_params.exec_time = 0; /* reset budget */
+		}
+		else {
+			TRACE_TASK(t, "adjustment falls below threshold. %lld < %lld\n",
+				diff, ADJUSTMENT_THRESH_US);
+		}
+	}
+	else {
+		TRACE_TASK(t, "got tokens early--no need to adjust release. "
+			"cur time = %llu, release time = %llu\n",
+			now, tsk_rt(t)->job_params.release);
+	}
+}
-- 
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