Date: Thu, 19 Sep 1996 09:06:25 -0600 (MDT) From: Nate Williams <nate@mt.sri.com> To: Poul-Henning Kamp <phk@freefall.freebsd.org> Cc: CVS-committers@freefall.freebsd.org, mobile@freefall.freebsd.org Subject: Re: cvs commit: src/sys/i386/i386 swtch.s src/sys/i386/conf LINT Message-ID: <199609191506.JAA18010@rocky.mt.sri.com> In-Reply-To: <199609190828.BAA14440@freefall.freebsd.org> References: <199609190828.BAA14440@freefall.freebsd.org>
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> Modified: sys/i386/conf LINT > sys/i386/i386 swtch.s > Log: > Add APM_IDLE_CPU option, that is off by default. > I maintain that it saves more power to simply "hlt" the CPU than to > spend tons of time trying to tell the APM bios to do the same. > In particular if you do it 100 times a second... FWIW, I sort of agree with Poul here. He asked me to do some timing tests on my laptops (which I actually did), and it appears that doing the idle/busy stuff on one of my laptops made very little difference. I got an extra 9 minutes with the APM code enabled 3 hours, 10 minutes vs 3 hours and 1 minutes with it disabled. However, this was one run on a fairly modern latop. I want to try testing on the other three models I have lying around, but other committments have been brutal. If other folks could test out disabling the idle stuff it would be great. Power cycle your battery a couple times to make sure you aren't affected by that, and then power it up full. Boot a kernel with the busy/idle loop enabled (the default), enable apm (apmconf -e), unplug it and wait until it suspends. Mark the time down and do the same thing with a kernel with the above option enabled and see what you get. Poul and I have talked about this already, and we think that a hueristic which determines 'a period' of idleness would be a better solution. That way we could kick it into 'apm_idle' if the machine has been idle for X cycles rather than kicking it in and out *all* the time. Nate
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