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Groups > linux.kernel > #1475522

[RFC/RFT][PATCH 1/4] cpufreq / sched: SCHED_CPUFREQ_IOWAIT flag to indicate iowait condition

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From: Rafael J. Wysocki <rafael.j.wysocki@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
SCHED_CPUFREQ_IOWAIT 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() may not be invoked in that case.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@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
@@ -4500,6 +4500,14 @@ enqueue_task_fair(struct rq *rq, struct
 	struct cfs_rq *cfs_rq;
 	struct sched_entity *se = &p->se;
 
+	/*
+	 * If in_iowait is set, the code below may not trigger any cpufreq
+	 * utilization updates, so do it here explicitly with the IOWAIT flag
+	 * passed.
+	 */
+	if (p->in_iowait)
+		cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IOWAIT);
+
 	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
@@ -3471,6 +3471,7 @@ static inline unsigned long rlimit_max(u
 
 #define SCHED_CPUFREQ_RT	(1U << 0)
 #define SCHED_CPUFREQ_DL	(1U << 1)
+#define SCHED_CPUFREQ_IOWAIT	(1U << 2)
 
 #define SCHED_CPUFREQ_RT_DL	(SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL)
 

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[RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in intel_pstate and schedutil "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-03 03:00 +0200
  [RFC/RFT][PATCH 3/4] cpufreq: intel_pstate: Use average P-state in get_target_pstate_default() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-03 03:00 +0200
  [RFC/RFT][PATCH 1/4] cpufreq / sched: SCHED_CPUFREQ_IOWAIT flag to indicate iowait condition "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-03 03:00 +0200
  [RFC/RFT][PATCH 4/4] cpufreq: schedutil: Add iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-03 03:00 +0200
  [RFC/RFT][PATCH 2/4]  cpufreq: intel_pstate: Change P-state selection algorithm for Core "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-03 03:10 +0200
  RE: [RFC/RFT][PATCH 2/4]  cpufreq: intel_pstate: Change P-state selection algorithm for Core "Doug Smythies" <dsmythies@telus.net> - 2016-09-07 17:30 +0200
  Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Steve Muckle <steve.muckle@linaro.org> - 2016-09-08 02:30 +0200
    Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> - 2016-09-08 02:40 +0200
      Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in intel_pstate and schedutil "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-08 02:40 +0200
        Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> - 2016-09-08 02:50 +0200
          Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in intel_pstate and schedutil "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-08 03:20 +0200
            Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in intel_pstate and schedutil "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-08 17:00 +0200
              Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> - 2016-09-08 19:40 +0200
      Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Steve Muckle <steve.muckle@linaro.org> - 2016-09-08 21:30 +0200
        Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in  intel_pstate and schedutil Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> - 2016-09-08 21:50 +0200
    Re: [RFC/RFT][PATCH 0/4] cpufreq / sched: iowait boost in intel_pstate and schedutil "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-08 02:40 +0200

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