Re: Is the C3 possible with SMP?
Alexander Motin <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.mobile,gmane.os.freebsd.devel.acpi |
|---|---|
| Message-ID | <[email protected]> |
Alexandre "Sunny" Kovalenko wrote: >> I have tried to enable C3 state on my Core2Duo laptop and found that it >> is not working good. System HZ timer stops during CPU sleep. After some >> investigation I have found that it is due to LAPIC timer used for HZ >> stopped during C3 state (same as during AMD's C1E). >> >> So the question is: Is it possible (or planned) to make it work somehow? >> For example, by using some external timer instead of LAPIC's one? >> >> ACPI reports about 20% less idle power consumption with C3 state >> comparing to C2. It would be interesting to get additional half an hour >> on battery. >> > You can get half way there by adding > > dev.cpu.1.cx_lowest=C3 > > to /etc/sysctl.conf Thanks. 1. Looks like it does not kill the timer. 2. I haven't got any benefit from it in idle state. According to `acpiconf -i 0` I have about 13 Amps (IMHO more looks like Watts) with both C2 and this half-to-C3, but only 11 Amps in full C3 (but without timer). 3. I have got about 10% benefit (33 Amps against 36) when cpu0 is 100% busy while cpu1 is idle. -- Alexander Motin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-mobile To unsubscribe, send any mail to "[email protected]"