On Friday 11 September 2009 11:46:13 am Pierre-Luc Drouin wrote: > John Baldwin wrote: > > On Thursday 10 September 2009 8:57:32 pm Pierre-Luc Drouin wrote: > > > >> Hi, > >> > >> I have an overclocked i7 920 CPU for which I have enabled Turbo Mode in > >> the BIOS (21x multiplier). The base clock is set at 190 MHz, so the CPU > >> frequency with Turbo mode activated should be 3990 MHz. However the > >> maximum value FreeBSD amd64 shows for the CPU frequency in dmesg and > >> sysctl is 3790 MHz. How can I enable the Turbo Mode? > >> > >> CPU: Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz (3790.52-MHz > >> K8-class CPU) > >> > >> machdep.acpi_timer_freq: 3579545 > >> machdep.tsc_freq: 3790522507 > >> machdep.i8254_freq: 1193182 > >> dev.cpu.0.freq: 349 > >> dev.cpu.0.freq_levels: 2793/130000 2443/113750 2094/97500 1745/81250 > >> 1396/65000 1047/48750 698/32500 349/16250 > >> > > > > You have to enable C2/C3 sleep states (possibly in your BIOS). However, > > FreeBD doesn't currently handle this but so well since that will probably > > turn off the local APIC timer interrupt when the CPU is idle causing FreeBSD > > to miss clock interrupts. > > > > > Sorry I am not sure exactly what you are referring to. Do you mean that > I need to enable C2/C3 states in order to have the correct max CPU freq > value displayed at boot time/in sysctl, or you mean that I need these > states in order to be able to use the Turbo Mode at all? Right now in > the BIOS I had the following features disabled to test the overclocking > (I was following what is recommended to do for Windows users to run > stress tests): > > -Intel SpeedStep: Use this function to enable the Intel SpeedStep > technology (EIST) > -CxE Function: This function allows you to select the lowest C state > supported according as CPU and MB. The options are Auto, Disabled, C1, > C1E, C3 and C6
You need to have C2/C3 enabled for it to work at all, at least on Nehalem processors. -- John Baldwin _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
