-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Eddy Petrișor wrote: > Florian Reitmeir wrote: >> Hi, > >> On Mon, 05 Feb 2007, Eddy Petri??or wrote: > >>> On a side note, I have found out that FreeBSD is able to bring down the >>> processor speed of a Pentium M processor on a laptop of a friend a LOT >>> lower than what Linux is able to do (200MHz as opposed to 800MHz in Linux). >>> >>> I am wondering if the information is correct. I thought of installing >>> Debian GNU/kFreeBSD but I failed miserably and I don't know when and if >>> I'll try again. >> I know these patches. The 200mhz are only shown in the kernel (in my case >> linux) but the hardware is not capable of that, look for your self into the >> intel datasheets. > >> But indeed its possible to "undervolt" the cpu to save power, approx. 10-20%, >> search for the linux-phc patches. > >> https://www.dedigentoo.org/trac/linux-phc/ > > This seems to apply only to older cores. I have a Intel Core 2 Duo > processor. Anybody knows if this is supported? i browsed the forums on > gentoo and found that someone provided baz some info on the Core 2 Duo, > but I don't know what is the current status.
I have installed Debian GNU/kFreeBSD and indeed, the levels are many more than on Linux: sysctl dev.cpu.0.freq_levels Results in a list of frequencies down to 31 MHz. I tried some script I found on the freebsd lists[1] to test the speed of blowfish at various speeds and observed that on my Core 2 Duo that: - - speed does not go linearly down with the scaling of the frequency - some of the frequencies like 750, 500, 250 were actually more slower than the previous ones, but the interim values were faster. - - starting downwards from (I think, but I am not sure) 750 MHz, there were some ugly debugging messages that seem to originate from libc or something similar (sorry, I don't have the output due to the following) - - after running a while (2-3 min) at a low speed the system freezes, probably the cpu goes mad :-) - I have tested this and it happens on my system (starting from low speeds upwards) up to 500MHz, including that frequency. So I am thinking that maybe, just maybe, 750MHz would be stable enough, but I haven't found the time to test. This would be uber-cool in long trips during which I read stuff or hack on stuff (without compiling) in case of mock-ups or similar situations. In conclusion, it would be nice if this code would be ported to Linux, too. BTW, I like the sysctl aproach they use in kFreeBSD instead of proc/sys, it seems more intuitive. [1] http://lists.freebsd.org/pipermail/freebsd-acpi/2005-July/001695.html - -- Regards, EddyP ============================================= "Imagination is more important than knowledge" A.Einstein -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFF1NAAY8Chqv3NRNoRAqmbAJwOc1XyTu0kJS9LgZN69iFbzs9eHACgyoPo 94S0AZ6UUKxcfBADtflaMYE= =/BZ1 -----END PGP SIGNATURE----- -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
