From: Ingo Molnar <mingo@elte.hu>
- minor can_migrate_task cleanup
kernel/sched.c | 27 +++++++++++----------------
1 files changed, 11 insertions(+), 16 deletions(-)
diff -puN kernel/sched.c~sched-can-migrate-2.6.0-A2 kernel/sched.c
--- 25/kernel/sched.c~sched-can-migrate-2.6.0-A2 2003-12-30 00:45:12.000000000 -0800
+++ 25-akpm/kernel/sched.c 2003-12-30 00:45:12.000000000 -0800
@@ -1146,25 +1146,25 @@ static inline void pull_task(runqueue_t
}
/*
- * Previously:
- *
- * #define CAN_MIGRATE_TASK(p,rq,this_cpu) \
- * ((!idle || (NS_TO_JIFFIES(now - (p)->timestamp) > \
- * cache_decay_ticks)) && !task_running(rq, p) && \
- * cpu_isset(this_cpu, (p)->cpus_allowed))
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
-
static inline int
can_migrate_task(task_t *tsk, runqueue_t *rq, int this_cpu, int idle)
{
unsigned long delta = rq->timestamp_last_tick - tsk->timestamp;
- if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks)))
- return 0;
+ /*
+ * We do not migrate tasks that are:
+ * 1) running (obviously), or
+ * 2) cannot be migrated to this CPU due to cpus_allowed, or
+ * 3) are cache-hot on their current CPU.
+ */
if (task_running(rq, tsk))
return 0;
if (!cpu_isset(this_cpu, tsk->cpus_allowed))
return 0;
+ if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks)))
+ return 0;
return 1;
}
@@ -1226,13 +1226,6 @@ skip_bitmap:
skip_queue:
tmp = list_entry(curr, task_t, run_list);
- /*
- * We do not migrate tasks that are:
- * 1) running (obviously), or
- * 2) cannot be migrated to this CPU due to cpus_allowed, or
- * 3) are cache-hot on their current CPU.
- */
-
curr = curr->prev;
if (!can_migrate_task(tmp, busiest, this_cpu, idle)) {
@@ -1242,6 +1235,8 @@ skip_queue:
goto skip_bitmap;
}
pull_task(busiest, array, tmp, this_rq, this_cpu);
+
+ /* Only migrate one task if we are idle */
if (!idle && --imbalance) {
if (curr != head)
goto skip_queue;
_