Hi, My first question was why CPU states are different from BIOS? If C4 and C5 are good, why and for what reason, the BIOS does not support it. This means that BIOS does not like power saving sates (!) After that I wondered why my system does not even support C3. So you and Edward said that C3 is mapped to C6. It is understanable that OS map C3 to C6, but since ACPI is a standard, why should CPU, BIOS and OS each one say something different. I am not so expert but I think it is a little bit confusing. -------------------------- *Mahmood Naderan* On 6/22/09, yakui_zhao <yakui.zhao@xxxxxxxxx> wrote: > On Sun, 2009-06-21 at 17:20 +0800, Mahmood Naderan wrote: > > 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)? > What is your problem? > > The following info only tells us that the following CPU C-state is > supported on the CPU. > >Your CPU supports the following C-states : C1 C2 C3 C4 C5 C6 > > But not all the CPU C-state is not used by the OS. > It seems that the C1/C2/C6 is used on this box. > > At the same time it is noted that the cpu C-state is different with the > ACPI C-state. In fact BIOS will do the mapping between the CPU C-state > and ACPI C-state. And ACPI C-state is used by the OS. > For example: on your box: The CPU C6 is mapped to ACPI C3-state. > > >From the info of "cat /proc/acpi/processor/CPU*/power" we know that your > box can enter the ACPI C3, which is mapped to the CPU C6. Of course it > is the deep C-state. > > Thanks. > > > > > -------------------------- > > *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 > > -- 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
