From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Testing indicates that it is possible to improve performace
significantly without increasing energy consumption too much by
teaching cpufreq governors to bump up the CPU performance level if
the in_iowait flag is set for the task in enqueue_task_fair().
For this purpose, define a new cpufreq_update_util() flag
UUF_IO and modify enqueue_task_fair() to pass that flag to
cpufreq_update_util() in the in_iowait case. That generally
requires cpufreq_update_util() to be called directly from there,
because update_load_avg() is not likely to be invoked in that
case.
Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
---
include/linux/sched.h | 1 +
kernel/sched/fair.c | 8 ++++++++
2 files changed, 9 insertions(+)
Index: linux-pm/kernel/sched/fair.c
===================================================================
--- linux-pm.orig/kernel/sched/fair.c
+++ linux-pm/kernel/sched/fair.c
@@ -4459,6 +4459,14 @@ enqueue_task_fair(struct rq *rq, struct
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
+ /*
+ * If in_iowait is set, it is likely that the loops below will not
+ * trigger any cpufreq utilization updates, so do it here explicitly
+ * with the IO flag passed.
+ */
+ if (p->in_iowait)
+ cpufreq_update_util(rq, UUF_IO);
+
for_each_sched_entity(se) {
if (se->on_rq)
break;
Index: linux-pm/include/linux/sched.h
===================================================================
--- linux-pm.orig/include/linux/sched.h
+++ linux-pm/include/linux/sched.h
@@ -3376,6 +3376,7 @@ static inline unsigned long rlimit_max(u
}
#define UUF_RT 0x01
+#define UUF_IO 0x02
#ifdef CONFIG_CPU_FREQ
struct update_util_data {
