sched: Remove avg_wakeup

Testing the load which led to this heuristic (nfs4 kbuild) shows that it has
outlived it's usefullness.  With intervening load balancing changes, I cannot
see any difference with/without, so recover there fastpath cycles.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301062.6785.29.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 13efe7d..70c560f 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1185,9 +1185,6 @@ struct sched_entity {
 
        u64                     nr_migrations;
 
-       u64                     start_runtime;
-       u64                     avg_wakeup;
-
 #ifdef CONFIG_SCHEDSTATS
        struct sched_statistics statistics;
 #endif

diff --git a/kernel/sched.c b/kernel/sched.c
index 60b1bbe..35a8626 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1880,9 +1880,6 @@ static void update_avg(u64 *avg, u64 sample)
 static void
 enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, bool head)
 {
-       if (wakeup)
-               p->se.start_runtime = p->se.sum_exec_runtime;
-
        sched_info_queued(p);
        p->sched_class->enqueue_task(rq, p, wakeup, head);
        p->se.on_rq = 1;
@@ -1890,17 +1887,11 @@ enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, bool head)
 
 static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
 {
-       if (sleep) {
-               if (p->se.last_wakeup) {
-                       update_avg(&p->se.avg_overlap,
-                               p->se.sum_exec_runtime - p->se.last_wakeup);
-                       p->se.last_wakeup = 0;
-               } else {
-                       update_avg(&p->se.avg_wakeup,
-                               sysctl_sched_wakeup_granularity);
-               }
+       if (sleep && p->se.last_wakeup) {
+               update_avg(&p->se.avg_overlap,
+                       p->se.sum_exec_runtime - p->se.last_wakeup);
+               p->se.last_wakeup = 0;
        }
-
        sched_info_dequeued(p);
        p->sched_class->dequeue_task(rq, p, sleep);
        p->se.on_rq = 0;
@@ -2466,13 +2457,6 @@ out_activate:
         */
        if (!in_interrupt()) {
                struct sched_entity *se = &current->se;
-               u64 sample = se->sum_exec_runtime;
-
-               if (se->last_wakeup)
-                       sample -= se->last_wakeup;
-               else
-                       sample -= se->start_runtime;
-               update_avg(&se->avg_wakeup, sample);
 
                se->last_wakeup = se->sum_exec_runtime;
        }
@@ -2540,8 +2524,6 @@ static void __sched_fork(struct task_struct *p)
        p->se.nr_migrations             = 0;
        p->se.last_wakeup               = 0;
        p->se.avg_overlap               = 0;
-       p->se.start_runtime             = 0;
-       p->se.avg_wakeup                = sysctl_sched_wakeup_granularity;
 
 #ifdef CONFIG_SCHEDSTATS
        memset(&p->se.statistics, 0, sizeof(p->se.statistics));

diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index ad9df44..20b95a4 100644 (file)
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -408,7 +408,6 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
        PN(se.vruntime);
        PN(se.sum_exec_runtime);
        PN(se.avg_overlap);
-       PN(se.avg_wakeup);
 
        nr_switches = p->nvcsw + p->nivcsw;
 

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 8ad164b..6fc6285 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1592,42 +1592,11 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
 }
 #endif /* CONFIG_SMP */
 
-/*
- * Adaptive granularity
- *
- * se->avg_wakeup gives the average time a task runs until it does a wakeup,
- * with the limit of wakeup_gran -- when it never does a wakeup.
- *
- * So the smaller avg_wakeup is the faster we want this task to preempt,
- * but we don't want to treat the preemptee unfairly and therefore allow it
- * to run for at least the amount of time we'd like to run.
- *
- * NOTE: we use 2*avg_wakeup to increase the probability of actually doing one
- *
- * NOTE: we use *nr_running to scale with load, this nicely matches the
- *       degrading latency on load.
- */
-static unsigned long
-adaptive_gran(struct sched_entity *curr, struct sched_entity *se)
-{
-       u64 this_run = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
-       u64 expected_wakeup = 2*se->avg_wakeup * cfs_rq_of(se)->nr_running;
-       u64 gran = 0;
-
-       if (this_run < expected_wakeup)
-               gran = expected_wakeup - this_run;
-
-       return min_t(s64, gran, sysctl_sched_wakeup_granularity);
-}
-
 static unsigned long
 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
 {
        unsigned long gran = sysctl_sched_wakeup_granularity;
 
-       if (cfs_rq_of(curr)->curr && sched_feat(ADAPTIVE_GRAN))
-               gran = adaptive_gran(curr, se);
-
        /*
         * Since its curr running now, convert the gran from real-time
         * to virtual-time in his units.

diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index d5059fd..96ef5db 100644 (file)
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -31,12 +31,6 @@ SCHED_FEAT(START_DEBIT, 1)
 SCHED_FEAT(WAKEUP_PREEMPT, 1)
 
 /*
- * Compute wakeup_gran based on task behaviour, clipped to
- *  [0, sched_wakeup_gran_ns]
- */
-SCHED_FEAT(ADAPTIVE_GRAN, 1)
-
-/*
  * When converting the wakeup granularity to virtual time, do it such
  * that heavier tasks preempting a lighter task have an edge.
  */