linux-kernel - [PATCH] cpufreq: intel_pstate: Drop boost

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Message-ID: <3255301.amKi4OUQkX@vostro.rjw.lan>
Date:   Wed, 19 Oct 2016 02:53:26 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM list <linux-pm@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] cpufreq: intel_pstate: Drop boost_iowait flag

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

The "IOwait boosting" mechanism is only used by the
get_target_pstate_use_cpu_load() governor function and the
boost_iowait flag in pid_params is always set when that function
is in use (and it is never set otherwise).  This means that the
boost_iowait flag is in fact redundant and may be dropped.

For this reason, replace the boost_iowait flag check in
intel_pstate_update_util() with an equivalent check against
pstate_funcs.get_target_pstate and drop that flag.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -233,7 +233,6 @@ static struct cpudata **all_cpu_data;
  * @p_gain_pct:		PID proportional gain
  * @i_gain_pct:		PID integral gain
  * @d_gain_pct:		PID derivative gain
- * @boost_iowait:	Whether or not to use iowait boosting.
  *
  * Stores per CPU model static PID configuration data.
  */
@@ -245,7 +244,6 @@ struct pstate_adjust_policy {
 	int p_gain_pct;
 	int d_gain_pct;
 	int i_gain_pct;
-	bool boost_iowait;
 };
 
 /**
@@ -1043,7 +1041,6 @@ static const struct cpu_defaults silverm
 		.p_gain_pct = 14,
 		.d_gain_pct = 0,
 		.i_gain_pct = 4,
-		.boost_iowait = true,
 	},
 	.funcs = {
 		.get_max = atom_get_max_pstate,
@@ -1065,7 +1062,6 @@ static const struct cpu_defaults airmont
 		.p_gain_pct = 14,
 		.d_gain_pct = 0,
 		.i_gain_pct = 4,
-		.boost_iowait = true,
 	},
 	.funcs = {
 		.get_max = atom_get_max_pstate,
@@ -1107,7 +1103,6 @@ static const struct cpu_defaults bxt_par
 		.p_gain_pct = 14,
 		.d_gain_pct = 0,
 		.i_gain_pct = 4,
-		.boost_iowait = true,
 	},
 	.funcs = {
 		.get_max = core_get_max_pstate,
@@ -1346,7 +1341,7 @@ static void intel_pstate_update_util(str
 	struct cpudata *cpu = container_of(data, struct cpudata, update_util);
 	u64 delta_ns;
 
-	if (pid_params.boost_iowait) {
+	if (pstate_funcs.get_target_pstate == get_target_pstate_use_cpu_load) {
 		if (flags & SCHED_CPUFREQ_IOWAIT) {
 			cpu->iowait_boost = int_tofp(1);
 		} else if (cpu->iowait_boost) {