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Message-ID: <20071011220015.27097.74545.stgit@novell1.haskins.net>
Date: Thu, 11 Oct 2007 18:00:15 -0400
From: Gregory Haskins <ghaskins@...ell.com>
To: Steven Rostedt <rostedt@...dmis.org>,
Peter Zijlstra <peterz@...radead.org>
Cc: linux-rt-users <linux-rt-users@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Gregory Haskins <ghaskins@...ell.com>
Subject: [PATCH 6/7] RT: Convert Steve's rt-push infrastructure to cpupri
Normalize the CPU priority system between the two search algorithms, and
modularlize the search function within push_rt_tasks.
Signed-off-by: Gregory Haskins <ghaskins@...ell.com>
---
kernel/sched.c | 91 ++++++++++++++++++++++++++++++++++++++------------------
1 files changed, 61 insertions(+), 30 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 0065551..e8942c5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -24,6 +24,7 @@
* by Peter Williams
* 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
* 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
+ * 2007-10-11 RT overload enhancements by Steven Rostedt, Greg Haskins
*/
#include <linux/mm.h>
@@ -305,8 +306,10 @@ struct rq {
#ifdef CONFIG_PREEMPT_RT
unsigned long rt_nr_running;
unsigned long rt_nr_uninterruptible;
+#ifndef CONFIG_CPU_PRIORITIES
int curr_prio;
#endif
+#endif
unsigned long switch_timestamp;
unsigned long slice_avg;
@@ -501,9 +504,48 @@ static int get_cpupri(struct rq *rq)
return cpupri_get(rq->cpu);
}
+static int find_lowest_cpu(int defcpu, int pri, struct task_struct *p)
+{
+ return cpupri_find_best(defcpu, pri, p);
+}
#else
-#define set_cpupri(rq, task) do { } while (0)
-#define get_cpupri(rq) CPUPRI_INVALID
+static void set_cpupri(struct rq *rq, struct task_struct *p)
+{
+ rq->curr_prio = calc_task_cpupri(rq, p);
+}
+
+static int get_cpupri(struct rq *rq)
+{
+ return rq->curr_prio;
+}
+
+static int find_lowest_cpu(int defcpu, int pri, struct task_struct *p)
+{
+ cpumask_t mask;
+ int cpu;
+ struct rq *lowest_rq = NULL;
+
+ cpus_and(mask, cpu_online_map, p->cpus_allowed);
+
+ /*
+ * Scan each rq for the lowest prio.
+ */
+ for_each_cpu_mask(cpu, mask) {
+ struct rq *rq = &per_cpu(runqueues, cpu);
+
+ if (cpu == smp_processor_id())
+ continue;
+
+ /* no locking for now */
+ if (rq->curr_prio < pri &&
+ (!lowest_rq || rq->curr_prio < lowest_rq->curr_prio)) {
+ lowest_rq = rq;
+ }
+ }
+
+ return lowest_rq ? lowest_rq->cpu : defcpu;
+}
+
#endif
/*
@@ -1531,11 +1573,9 @@ static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
static int push_rt_task(struct rq *this_rq)
{
struct task_struct *next_task;
- struct rq *lowest_rq = NULL;
int tries;
- int cpu;
- int dst_cpu = -1;
int ret = 0;
+ int pri;
assert_spin_locked(&this_rq->lock);
@@ -1546,32 +1586,19 @@ static int push_rt_task(struct rq *this_rq)
/* We might release this_rq lock */
get_task_struct(next_task);
+ pri = calc_task_cpupri(this_rq, next_task);
+
/* Only try this algorithm three times */
for (tries = 0; tries < 3; tries++) {
- cpumask_t mask;
-
- cpus_and(mask, cpu_online_map, next_task->cpus_allowed);
-
- /*
- * Scan each rq for the lowest prio.
- */
- for_each_cpu_mask(cpu, mask) {
- struct rq *rq = &per_cpu(runqueues, cpu);
-
- if (cpu == smp_processor_id())
- continue;
-
- /* no locking for now */
- if (rq->curr_prio > next_task->prio &&
- (!lowest_rq || rq->curr_prio < lowest_rq->curr_prio)) {
- dst_cpu = cpu;
- lowest_rq = rq;
- }
- }
+ struct rq *lowest_rq;
+ int cpu;
- if (!lowest_rq)
+ cpu = find_lowest_cpu(this_rq->cpu, pri, next_task);
+ if (cpu == this_rq->cpu)
break;
+ lowest_rq = cpu_rq(cpu);
+
if (double_lock_balance(this_rq, lowest_rq)) {
/*
* We had to unlock the run queue. In
@@ -1579,20 +1606,20 @@ static int push_rt_task(struct rq *this_rq)
* migrated already or had its affinity changed.
*/
if (unlikely(task_rq(next_task) != this_rq ||
- !cpu_isset(dst_cpu, next_task->cpus_allowed))) {
+ !cpu_isset(cpu, next_task->cpus_allowed))) {
spin_unlock(&lowest_rq->lock);
break;
}
}
/* if the prio of this runqueue changed, try again */
- if (lowest_rq->curr_prio <= next_task->prio) {
+ if (get_cpupri(lowest_rq) > pri) {
spin_unlock(&lowest_rq->lock);
continue;
}
deactivate_task(this_rq, next_task, 0);
- set_task_cpu(next_task, dst_cpu);
+ set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0);
resched_task(lowest_rq->curr);
@@ -2333,7 +2360,7 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
* If we pushed an RT task off the runqueue,
* then kick other CPUs, they might run it:
*/
- rq->curr_prio = current->prio;
+
if (unlikely(rq->rt_nr_running > 1))
push_rt_task(rq);
@@ -7371,6 +7398,10 @@ void __init sched_init(void)
highest_cpu = i;
/* delimiter for bitsearch: */
__set_bit(MAX_RT_PRIO, array->bitmap);
+
+#if defined(CONFIG_PREEMPT_RT) && !defined(CONFIG_CPU_PRIORITIES)
+ rq->curr_prio = CPUPRI_INVALID;
+#endif
}
set_load_weight(&init_task);
-
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