I got more confused... In my first post if you see, BIOS reports C1, C2 and C6. Even it does not support C3 (!), but here is the output of "cat /proc/acpi/processor/CPU0/power": active state: C0 max_cstate: C8 bus master activity: 00000000 maximum allowed latency: 2000000000 usec states: C1: type[C1] promotion[--] demotion[--] latency[001] usage[00000063] duration[00000000000000000000] C2: type[C2] promotion[--] demotion[--] latency[001] usage[00017466] duration[00000000000014422985] C3: type[C3] promotion[--] demotion[--] latency[162] usage[00096196] duration[00000000000650582389] So I think something (BIOS or CPU or OS) is malfunctioning and does not report correctly. Now the big question is, will my system (a combination of CPU, BIOS and OS) enter C3 (or even deeper states)? -------------------------- *Mahmood Naderan* On Sun, Jun 21, 2009 at 2:34 AM, Ananth Narayan S<ananth.narayan@xxxxxxxxx> wrote: > You could see it that way. The OS will use the C states exported by > the BIOS. If C4/C5 are not exported, the OS will not even know that > such states exist. If you query /proc/acpi/CPU*/power, you'll probably > see just three C states listed (C1, C2, C3). Typically the last > C-state (C3) in that will map to the lowest C-state supported by the > processor. > > -- Ananth > > > > > On Sat, Jun 20, 2009 at 8:46 AM, Mahmood Naderan<mahmood.nt@xxxxxxxxx> wrote: >> Hi, >> So if my understanding is correct, the BIOS does not allow the CPU to >> enter C4 and C5 states. Right? >> >> -------------------------- >> *Mahmood Naderan* >> >> >> >> >> On Sat, Jun 20, 2009 at 7:56 PM, Ananth Narayan >> S<ananth.narayan@xxxxxxxxx> wrote: >>> Intel processors export a max supported c state value. But when it >>> comes to c states, typically the one that provides max power savings >>> is exported by the BIOS. The intermediate ones aren't. >>> >>> -- Ananth Narayan S. >>> >>> >>> >>> >>> On Fri, Jun 19, 2009 at 10:07 AM, Mahmood Naderan<mahmood.nt@xxxxxxxxx> wrote: >>>> Hi, >>>> I have run powertop with root permission with both AC and batter powers. The >>>> reported C_States are the same and strange: >>>> >>>> mahmood@magma:~$ sudo powertop >>>> PowerTOP 1.11 (C) 2007, 2008 Intel Corporation >>>> >>>> Collecting data for 5 seconds >>>> >>>> Your CPU supports the following C-states : C1 C2 C3 C4 C5 C6 >>>> Your BIOS reports the following C-states : C1 C2 C6 >>>> >>>> Where are C4 and C5? >>>> >>>> -------------------------- >>>> *Mahmood Naderan* >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
