Index: powerd.c
===================================================================
RCS file: /home/ncvs/src/usr.sbin/powerd/powerd.c,v
retrieving revision 1.20
diff -u -p -r1.20 powerd.c
--- powerd.c	19 Feb 2006 00:40:28 -0000	1.20
+++ powerd.c	3 May 2006 20:36:21 -0000
@@ -50,8 +50,8 @@ __FBSDID("$FreeBSD: src/usr.sbin/powerd/
 #include <machine/apm_bios.h>
 #endif
 
-#define DEFAULT_ACTIVE_PERCENT	65
-#define DEFAULT_IDLE_PERCENT	90
+#define DEFAULT_ACTIVE_PERCENT	50
+#define DEFAULT_IDLE_PERCENT	70
 #define DEFAULT_POLL_INTERVAL	500	/* Poll interval in milliseconds */
 
 typedef enum {
@@ -369,8 +369,8 @@ main(int argc, char * argv[])
 	int nfds;
 	struct pidfh *pfh = NULL;
 	const char *pidfile = NULL;
-	long idle, total;
-	int curfreq, *freqs, i, *mwatts, numfreqs;
+	long excess, idle, next_excess, old_excess, total;
+	int curfreq, freq, *freqs, i, *mwatts, numfreqs;
 	int ch, mode, mode_ac, mode_battery, mode_none;
 	uint64_t mjoules_used;
 	size_t len;
@@ -484,6 +484,8 @@ main(int argc, char * argv[])
 	signal(SIGTERM, handle_sigs);
 
 	/* Main loop. */
+	old_excess = 0;
+
 	for (;;) {
 		FD_ZERO(&fdset);
 		if (devd_pipe >= 0) {
@@ -585,38 +587,67 @@ main(int argc, char * argv[])
 		}
 
 		/*
-		 * If we're idle less than the active mark, bump up two levels.
-		 * If we're idle more than the idle mark, drop down one level.
+		 * XXX describe PAST.
 		 */
 		for (i = 0; i < numfreqs - 1; i++) {
 			if (freqs[i] == curfreq)
 				break;
 		}
-		if (idle < (total * cpu_running_mark) / 100 &&
-		    curfreq < freqs[0]) {
-			i -= 2;
-			if (i < 0)
-				i = 0;
-			if (vflag) {
-				printf("idle time < %d%%, increasing clock"
-				    " speed from %d MHz to %d MHz\n",
-				    cpu_running_mark, curfreq, freqs[i]);
-			}
-			if (set_freq(freqs[i]))
-				err(1, "error setting CPU frequency %d",
-				    freqs[i]);
-		} else if (idle > (total * cpu_idle_mark) / 100 &&
-		    curfreq > freqs[numfreqs - 1]) {
-			i++;
-			if (vflag) {
-				printf("idle time > %d%%, decreasing clock"
-				    " speed from %d MHz to %d MHz\n",
-				    cpu_idle_mark, curfreq, freqs[i]);
-			}
-			if (set_freq(freqs[i]) != 0)
-				warn("error setting CPU frequency %d",
-				    freqs[i]);
+		next_excess = (total - idle) - (total * curfreq) / freqs[0];
+		excess = old_excess;
+		old_excess = next_excess;
+
+		if (excess < 0)
+			excess = 0;
+		total += excess;
+
+		if (curfreq < freqs[0]) {
+			if (excess > idle) {
+				if (vflag)
+					printf("excess > idle, setting to max frequency %d\n", freqs[0]);
+				if (set_freq(freqs[0]) != 0) {
+					warn("error setting CPU freq %d",
+				    	    freqs[0]);
+				}
+				continue;
+			}
+			if (idle < (total * cpu_running_mark) / 100) {
+				freq = curfreq -
+				    ((cpu_running_mark - cpu_idle_mark) *
+				        freqs[0]) / 100;
+				for (i = 0; i < numfreqs; i++) {
+					if (freqs[i] <= freq)
+						break;
+				}
+				if (freq == freqs[i])
+					i--;
+				if (i == 0)
+					i = 1;
+				if (vflag)
+					printf("idle < threshold, increasing clock speed %d\n", freqs[i]);
+				if (set_freq(freqs[i]))
+					warn("error setting CPU frequency %d",
+					    freqs[i]);
+				continue;
+			}
+		}
+
+		if (curfreq <= freqs[numfreqs - 1])
+			continue;
+
+		if (idle > (total * cpu_idle_mark) / 100) {
+			freq = curfreq - (((cpu_running_mark + cpu_idle_mark)/2 - (100 * (total - idle) / total)) * freqs[0]) / 100;
+			for (i = 0; i < numfreqs; i++) {
+				if (freqs[i] <= freq)
+					break;
+			}
+			if (vflag)
+				printf("idle > threshold, decreasing clock speed from %d to %d (actually %d)\n", curfreq, freq, freqs[i - 1]);
+			if (set_freq(freqs[i - 1]) != 0)
+				warn("error setting CPU freq %d",
+				    freqs[i - 1]);
 		}
+
 	}
 	free(freqs);
 	free(mwatts);