Date: Tue, 17 Apr 2001 01:45:24 -0400 From: parv <parv_@yahoo.com> To: John Baldwin <jhb@FreeBSD.org> Cc: Mike Smith <msmith@FreeBSD.org>, f-mobile <freebsd-mobile@FreeBSD.org>, Nate Williams <nate@yogotech.com> Subject: Re: observation: clock slows down when battery power gets low Message-ID: <20010417014524.A1023@moo.holy.cow> In-Reply-To: <XFMail.010416174813.jhb@FreeBSD.org> References: <200104162003.f3GK36513708@mass.dis.org> <XFMail.010416174813.jhb@FreeBSD.org>
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(i didn't get already quoted messages, so i will reply to this one,
the one i did get.)
so, John Baldwin shared this...
>
> On 16-Apr-01 Mike Smith wrote:
> >> > just an observation... on dell i5000e, clock slowed down
> >> > by about an hour and 10 minutes.
> >> > didn't see anything else
> >> > happening. i instinctively pressed the "power" button
> >> > when "power" led was not shining. nothing bad happened (of
> >> > course, apm is disabled.).
another observation: after i went from X to console, console screen
was flickering and there was a ghost image; reboot (after connecting
to 110V ac, of course) fixed the both problems. also, am running
freebsd 4.3 rc (apr 9 2001 9pm edt) if that matters.
> >>
> >> I think apm must be enabled for it to recognize the 'slowing' clock and
> >> deal with things correctly.
> >>
> >> Either that or completely disable power-savings...
how does one go about /completely/ disabling power-savings besides
not enabling apm? in any case, in bios, both "stand by" and
"suspend" options have been "disable"d, w/ "suspend to ram" and
"max performance" chosen for a long tiime.
> >
> > No, just don't use the TSC. The BIOS is winding the CPU clock back to
> > reduce power consumption, but the TSC code has no way of knowing that
> > this is going on.
being ignorant, how would winding back the clock (i am thinking of mechanical
wrist watch here) save power?
> >
> > Again - do not use the TSC. Got it yet? 8)
>
> That would be easier if not doing so wasn't so cryptic to figure out from a
> non-kernel hacker perspective, Mike. :)
>
> Parv,
>
> You want to do:
>
> sysctl -w kern.timecounter.hardware=i8254
>
> To make it more permament and easier, you can just stick
>
> kern.timecounter.hardware=i8254
>
> in /etc/sysctl.conf.
well, i was not explicitly using any particular clock calibration
and this was what i had when clock slowed down...
# dmesg | head -13
Copyright (c) 1992-2001 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD 4.3-RC #0: Thu Apr 12 01:07:27 EDT 2001
toor@moo.holy.cow:/usr/obj/usr/src/sys/BOVINE
Calibrating clock(s) ... TSC clock: 696960489 Hz, i8254 clock: 1193165 Hz
CLK_USE_I8254_CALIBRATION not specified - using default frequency
Timecounter "i8254" frequency 1193182 Hz
CLK_USE_TSC_CALIBRATION not specified - using old calibration method
CPU: Pentium III/Pentium III Xeon/Celeron (696.97-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0x686 Stepping = 6
Features=0x383f9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
real memory = 201326592 (196608K bytes)
# sysctl -a | grep -i timecount
kern.timecounter.method: 0
kern.timecounter.hardware: i8254
...after compiling the option CLK_USE_I8254_CALIBRATION in kernel,
sysctl shows the same informaion as above, and dmesg shows...
Copyright (c) 1992-2001 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD 4.3-RC #5: Tue Apr 17 00:41:34 EDT 2001
toor@moo.holy.cow:/usr/src/sys/compile/BOVINE
Calibrating clock(s) ... TSC clock: 696969498 Hz, i8254 clock: 1193180 Hz
Timecounter "i8254" frequency 1193180 Hz
CLK_USE_TSC_CALIBRATION not specified - using old calibration method
CPU: Pentium III/Pentium III Xeon/Celeron (696.97-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0x686 Stepping = 6
Features=0x383f9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
real memory = 201326592 (196608K bytes)
Physical memory chunk(s):
...am i missing something?
> We really should use hte i8254 by default on laptops. I have acpi turned on so
> the system even knows that it has a CPU that throttles, but it still uses the
> TSC by default. *sigh*
i suppose it was/is default, at least in my case, some how.
my, i never thought my observation would cause such a rucus! now that
it had, thanks everybody for sharing possible reasons & solutions.
- parv
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