Re: powerd(8)

In message <2304.1113826754_at_critter.freebsd.dk>, "Poul-Henning Kamp" writes:
>In message <4263A33A.3030201_at_centtech.com>, Eric Anderson writes:
>>Lukas Ertl wrote:
>>
>>There's been some discussion on the -mobile list (I believe) about
>>this kind of thing before.  I think powerd is currently running with
>>a 'best shot' configuration, and I'm pretty sure that if anyone has 
>>a better algorithm in a patch form for people to try, I'm certain the 
>>good people with commit bits would easily commit a patched better version.
>
>I don't think a proportional approach will work in this case, the steps
>are too far apart.
>
>I also think the switch to full speed is wrong.  Such see-saw
>algorithms waste far too much time decaying.  A less steep flank
>should be used.
>
>For instance:
>
>	if (idle > 90%)
>		reduce clock one step.
>	if (idle < 80%)
>		increase clock two steps.

Here's a patch which implements "phk" mode:


Index: powerd.c
===================================================================
RCS file: /home/ncvs/src/usr.sbin/powerd/powerd.c,v
retrieving revision 1.4
diff -u -r1.4 powerd.c
--- powerd.c	27 Feb 2005 01:58:49 -0000	1.4
+++ powerd.c	18 Apr 2005 12:26:03 -0000
_at__at_ -50,6 +50,7 _at__at_
 enum modes_t {
 	MODE_MIN,
 	MODE_ADAPTIVE,
+	MODE_PHK,
 	MODE_MAX,
 };
 
_at__at_ -220,6 +221,8 _at__at_
 		*mode = MODE_MAX;
 	else if (strcmp(arg, "adaptive") == 0)
 		*mode = MODE_ADAPTIVE;
+	else if (strcmp(arg, "phk") == 0)
+		*mode = MODE_PHK;
 	else
 		errx(1, "bad option: -%c %s", (char)ch, optarg);
 }
_at__at_ -377,6 +380,37 _at__at_
 		if (read_usage_times(&idle, &total))
 			err(1, "read_usage_times");
 
+		if (mode == MODE_PHK) {
+			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]))
+					err(1, "error setting CPU frequency %d", freqs[i]);
+			}
+			continue;
+		}
+
 		/*
 		 * If we're idle less than the active mark, jump the CPU to
 		 * its fastest speed if we're not there yet.  If we're idle

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.