linux-kernel - [PATCH v1 2/3] cpufreq: intel_pstate: Add and use hybrid_has

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Message-ID: <5025953.GXAFRqVoOG@rafael.j.wysocki>
Date: Wed, 08 Oct 2025 20:56:15 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Christian Loehle <christian.loehle@....com>
Subject: [PATCH v1 2/3] cpufreq: intel_pstate: Add and use hybrid_has_l3()

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

Introduce a function for checking whether or not a given CPU has L3
cache, called hybrid_has_l3(), and use it in hybrid_get_cost() for
computing cost coefficients associated with a given perf domain.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |   30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -951,11 +951,26 @@ static int hybrid_active_power(struct de
 	return 0;
 }

+static bool hybrid_has_l3(unsigned int cpu)
+{
+	struct cpu_cacheinfo *cacheinfo = get_cpu_cacheinfo(cpu);
+	unsigned int i;
+
+	if (!cacheinfo)
+		return false;
+
+	for (i = 0; i < cacheinfo->num_leaves; i++) {
+		if (cacheinfo->info_list[i].level == 3)
+			return true;
+	}
+
+	return false;
+}
+
 static int hybrid_get_cost(struct device *dev, unsigned long freq,
 			   unsigned long *cost)
 {
 	struct pstate_data *pstate = &all_cpu_data[dev->id]->pstate;
-	struct cpu_cacheinfo *cacheinfo = get_cpu_cacheinfo(dev->id);

 	/*
 	 * The smaller the perf-to-frequency scaling factor, the larger the IPC
@@ -973,17 +988,8 @@ static int hybrid_get_cost(struct device
 	 * touching it in case some other CPUs of the same type can do the work
 	 * without it.
 	 */
-	if (cacheinfo) {
-		unsigned int i;
-
-		/* Check if L3 cache is there. */
-		for (i = 0; i < cacheinfo->num_leaves; i++) {
-			if (cacheinfo->info_list[i].level == 3) {
-				*cost += 2;
-				break;
-			}
-		}
-	}
+	if (hybrid_has_l3(dev->id))
+		*cost += 2;

 	return 0;
 }