From: "Ted Unangst" <tedu@tedunangst.com>
Subject: cpu perfpolicy
To: tech@openbsd.org
Date: Sun, 01 Jun 2025 15:22:59 -0400

This introduces a helper function for hw.perfpolicy that allows more
machine specific policies to be set.

On my laptop, there's also a fan policy. This affects performance, but
it's not really related to the existing hw.setperf mechanism. For 
example, a "silent" fan setting and "high" CPU setting is reasonable.
Exactly what I want, in fact.

Fortunately, perfpolicy takes a string, which makes it flexible.
This uses two new optional functions to parse and append the policy.

hw.perfpolicy=silent,auto

Index: dev/acpi/acpiwmi.c
===================================================================
RCS file: /home/cvs/src/sys/dev/acpi/acpiwmi.c,v
diff -u -p -r1.5 acpiwmi.c
--- dev/acpi/acpiwmi.c	21 May 2025 02:18:29 -0000	1.5
+++ dev/acpi/acpiwmi.c	29 May 2025 01:15:42 -0000
@@ -311,6 +311,40 @@ asus_toggle(struct wmiasus *wh, int devi
 	asus_dev_set(wh, devid, *val | mask);
 }
 
+struct wmiasus *wmi_asus_policy_cookie;
+/* xxx the order may vary by machine... */
+static const char *asus_policies[] = { "standard,", "silent,", "perf," };
+
+void
+wmi_asus_setpolicy(char *policy)
+{
+	struct wmiasus *wh = wmi_asus_policy_cookie;
+	int target = -1;
+
+	for (int i = 0; i < nitems(asus_policies); i++) {
+		size_t len = strlen(asus_policies[i]);
+		if (strncmp(policy, asus_policies[i], len) == 0) {
+			target = i;
+			memmove(policy, policy + len, strlen(policy + len)+1);
+			break;
+		}
+	}
+	if (target != -1) {
+		wh->w_perf = target;
+		asus_dev_set(wh, wh->w_perfid, wh->w_perf);
+	}
+}
+
+void
+wmi_asus_getpolicy(char *policy, size_t len)
+{
+	struct wmiasus *wh = wmi_asus_policy_cookie;
+	int target = wh->w_perf;
+
+	if (target >= 0 && target < nitems(asus_policies))
+		strlcpy(policy, asus_policies[target], len);
+}
+
 static int
 wmi_asus_init(struct acpiwmi_softc *sc, struct guidinfo *ginfo)
 {
@@ -342,6 +376,13 @@ wmi_asus_init(struct acpiwmi_softc *sc, 
 	res = asus_dev_get(wh, ASUS_DEV_PERF_2);
 	if (res >= 0)
 		wh->w_perfid = ASUS_DEV_PERF_2;
+	if (wh->w_perfid != 0) {
+		extern void (*cpu_setpolicy)(char *);
+		extern void (*cpu_getpolicy)(char *, size_t);
+		cpu_getpolicy = wmi_asus_getpolicy;
+		cpu_setpolicy = wmi_asus_setpolicy;
+		wmi_asus_policy_cookie = wh;
+	}
 	// turn on by default
 	asus_toggle(wh, ASUS_DEV_KBDLIGHT, &wh->w_kbdlight);
 
Index: kern/sched_bsd.c
===================================================================
RCS file: /home/cvs/src/sys/kern/sched_bsd.c,v
diff -u -p -r1.100 sched_bsd.c
--- kern/sched_bsd.c	31 May 2025 06:58:27 -0000	1.100
+++ kern/sched_bsd.c	1 Jun 2025 07:48:21 -0000
@@ -541,6 +541,8 @@ schedclock(struct proc *p)
 }
 
 void (*cpu_setperf)(int);
+void (*cpu_setpolicy)(char *);
+void (*cpu_getpolicy)(char *, size_t);
 
 #define PERFPOL_MANUAL 0
 #define PERFPOL_AUTO 1
@@ -671,18 +673,22 @@ sysctl_hwperfpolicy(void *oldp, size_t *
 	if (!cpu_setperf)
 		return EOPNOTSUPP;
 
+	policy[0] = 0;
+	if (cpu_getpolicy)
+		cpu_getpolicy(policy, sizeof(policy));
+
 	switch (current_perfpolicy()) {
 	case PERFPOL_MANUAL:
-		strlcpy(policy, "manual", sizeof(policy));
+		strlcat(policy, "manual", sizeof(policy));
 		break;
 	case PERFPOL_AUTO:
-		strlcpy(policy, "auto", sizeof(policy));
+		strlcat(policy, "auto", sizeof(policy));
 		break;
 	case PERFPOL_HIGH:
-		strlcpy(policy, "high", sizeof(policy));
+		strlcat(policy, "high", sizeof(policy));
 		break;
 	default:
-		strlcpy(policy, "unknown", sizeof(policy));
+		strlcat(policy, "unknown", sizeof(policy));
 		break;
 	}
 
@@ -692,6 +698,9 @@ sysctl_hwperfpolicy(void *oldp, size_t *
 	err = sysctl_string(oldp, oldlenp, newp, newlen, policy, sizeof(policy));
 	if (err)
 		return err;
+
+	if (cpu_setpolicy)
+		cpu_setpolicy(policy);
 
 	policy_on_battery = strchr(policy, ',');
 	if (policy_on_battery != NULL) {