0128-itmt_epb-use-epb-to-scale-itmt.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan.van.de.ven@intel.com>
Date: Tue, 16 Nov 2021 17:39:25 +0000
Subject: [PATCH] itmt_epb: use epb to scale itmt

---
 arch/x86/include/asm/topology.h |  1 +
 arch/x86/kernel/cpu/intel_epb.c |  4 ++++
 arch/x86/kernel/itmt.c          | 29 ++++++++++++++++++++++++++++-
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 2f0b6be8eaab..c31f81e2ea05 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -174,6 +174,7 @@ extern unsigned int __read_mostly sysctl_sched_itmt_enabled;
 
 /* Interface to set priority of a cpu */
 void sched_set_itmt_core_prio(int prio, int core_cpu);
+void sched_set_itmt_power_ratio(int power_ratio, int core_cpu);
 
 /* Interface to notify scheduler that system supports ITMT */
 int sched_set_itmt_support(void);
diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
index fbaf12e43f41..c8c2d6f1a8ac 100644
--- a/arch/x86/kernel/cpu/intel_epb.c
+++ b/arch/x86/kernel/cpu/intel_epb.c
@@ -166,6 +166,10 @@ static ssize_t energy_perf_bias_store(struct device *dev,
 	if (ret < 0)
 		return ret;
 
+	/* update the ITMT scheduler logic to use the power policy data */
+	/* scale the val up by 2 so the range is 224 - 256 */
+	sched_set_itmt_power_ratio(256 - val * 2, cpu);
+
 	return count;
 }
 
diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c
index 57027bfed25f..596fd7fb7847 100644
--- a/arch/x86/kernel/itmt.c
+++ b/arch/x86/kernel/itmt.c
@@ -25,6 +25,7 @@
 
 static DEFINE_MUTEX(itmt_update_mutex);
 DEFINE_PER_CPU_READ_MOSTLY(int, sched_core_priority);
+DEFINE_PER_CPU_READ_MOSTLY(int, sched_power_ratio);
 
 /* Boolean to track if system has ITMT capabilities */
 static bool __read_mostly sched_itmt_capable;
@@ -169,7 +170,12 @@ void sched_clear_itmt_support(void)
 
 int arch_asym_cpu_priority(int cpu)
 {
-	return per_cpu(sched_core_priority, cpu);
+	int power_ratio = per_cpu(sched_power_ratio, cpu);
+
+	/* a power ratio of 0 (uninitialized) is assumed to be maximum */
+	if (power_ratio == 0)
+		power_ratio = 256 - 2 * 6;
+	return per_cpu(sched_core_priority, cpu) * power_ratio / 256;
 }
 
 extern int best_core;
@@ -217,3 +223,24 @@ void sched_set_itmt_core_prio(int prio, int core_cpu)
 		}
 	}
 }
+
+/**
+ * sched_set_itmt_power_ratio() - Set CPU priority based on ITMT
+ * @power_ratio:	The power scaling ratio [1..256] for the core
+ * @core_cpu:		The cpu number associated with the core
+ *
+ * Set a scaling to the cpu performance based on long term power
+ * settings (like EPB).
+ *
+ * Note this is for the policy not for the actual dynamic frequency;
+ * the frequency will increase itself as workloads run on a core.
+ */
+
+void sched_set_itmt_power_ratio(int power_ratio, int core_cpu)
+{
+	int cpu;
+
+	for_each_cpu(cpu, topology_sibling_cpumask(core_cpu)) {
+		per_cpu(sched_power_ratio, cpu) = power_ratio;
+	}
+}
-- 
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