[PATCH] Enable bit 11 in _PDC to advertise hw coord

[PATCH] Enable bit 11 in _PDC to advertise hw coord

[Pallipadi, Venkatesh]

Bit 11 in intel PDC definitions is meant for OS capability to handle
hardware coordination of P-states. In Linux we have always supported
hwardware coordination of P-states. Just let the BIOSes know that we
support it, by setting this bit.

Some BIOSes use this bit to choose between hardware or software coordination
and without this change below, BIOSes switch to software coordination, which
is not very optimal in terms of power consumption and extra wakeups from idle.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

---
 include/acpi/pdc_intel.h |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6/include/acpi/pdc_intel.h
===================================================================
--- linux-2.6.orig/include/acpi/pdc_intel.h	2009-01-20 16:11:20.000000000 -0800
+++ linux-2.6/include/acpi/pdc_intel.h	2009-02-02 10:32:06.000000000 -0800
@@ -14,6 +14,7 @@
 #define ACPI_PDC_SMP_T_SWCOORD		(0x0080)
 #define ACPI_PDC_C_C1_FFH		(0x0100)
 #define ACPI_PDC_C_C2C3_FFH		(0x0200)
+#define ACPI_PDC_SMP_P_HWCOORD		(0x0800)
 
 #define ACPI_PDC_EST_CAPABILITY_SMP	(ACPI_PDC_SMP_C1PT | \
 					 ACPI_PDC_C_C1_HALT | \
@@ -22,6 +23,7 @@
 #define ACPI_PDC_EST_CAPABILITY_SWSMP	(ACPI_PDC_SMP_C1PT | \
 					 ACPI_PDC_C_C1_HALT | \
 					 ACPI_PDC_SMP_P_SWCOORD | \
+					 ACPI_PDC_SMP_P_HWCOORD | \
 					 ACPI_PDC_P_FFH)
 
 #define ACPI_PDC_C_CAPABILITY_SMP	(ACPI_PDC_SMP_C2C3  | \

Re: [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Jens Axboe]

On Mon, Feb 02 2009, Pallipadi, Venkatesh wrote:
> 
> Bit 11 in intel PDC definitions is meant for OS capability to handle
> hardware coordination of P-states. In Linux we have always supported
> hwardware coordination of P-states. Just let the BIOSes know that we
> support it, by setting this bit.
> 
> Some BIOSes use this bit to choose between hardware or software coordination
> and without this change below, BIOSes switch to software coordination, which
> is not very optimal in terms of power consumption and extra wakeups from idle.

I can confirm that this fixes the excessive reschedule ipi count on an
x60 with the ondemand governor. Can we please get this into 2.6.29?

> 
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> 
> ---
>  include/acpi/pdc_intel.h |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux-2.6/include/acpi/pdc_intel.h
> ===================================================================
> --- linux-2.6.orig/include/acpi/pdc_intel.h	2009-01-20 16:11:20.000000000 -0800
> +++ linux-2.6/include/acpi/pdc_intel.h	2009-02-02 10:32:06.000000000 -0800
> @@ -14,6 +14,7 @@
>  #define ACPI_PDC_SMP_T_SWCOORD		(0x0080)
>  #define ACPI_PDC_C_C1_FFH		(0x0100)
>  #define ACPI_PDC_C_C2C3_FFH		(0x0200)
> +#define ACPI_PDC_SMP_P_HWCOORD		(0x0800)
>  
>  #define ACPI_PDC_EST_CAPABILITY_SMP	(ACPI_PDC_SMP_C1PT | \
>  					 ACPI_PDC_C_C1_HALT | \
> @@ -22,6 +23,7 @@
>  #define ACPI_PDC_EST_CAPABILITY_SWSMP	(ACPI_PDC_SMP_C1PT | \
>  					 ACPI_PDC_C_C1_HALT | \
>  					 ACPI_PDC_SMP_P_SWCOORD | \
> +					 ACPI_PDC_SMP_P_HWCOORD | \
>  					 ACPI_PDC_P_FFH)
>  
>  #define ACPI_PDC_C_CAPABILITY_SMP	(ACPI_PDC_SMP_C2C3  | \

-- 
Jens Axboe

Re: [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Henrique de Moraes Holschuh]

On Wed, 04 Feb 2009, Jens Axboe wrote:
> On Mon, Feb 02 2009, Pallipadi, Venkatesh wrote:
> > 
> > Bit 11 in intel PDC definitions is meant for OS capability to handle
> > hardware coordination of P-states. In Linux we have always supported
> > hwardware coordination of P-states. Just let the BIOSes know that we
> > support it, by setting this bit.
> > 
> > Some BIOSes use this bit to choose between hardware or software coordination
> > and without this change below, BIOSes switch to software coordination, which
> > is not very optimal in terms of power consumption and extra wakeups from idle.
> 
> I can confirm that this fixes the excessive reschedule ipi count on an
> x60 with the ondemand governor. Can we please get this into 2.6.29?

And, after that, -stable?

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Pallipadi, Venkatesh]

On Wed, 2009-02-04 at 11:53 -0800, Henrique de Moraes Holschuh wrote:
> On Wed, 04 Feb 2009, Jens Axboe wrote:
> > On Mon, Feb 02 2009, Pallipadi, Venkatesh wrote:
> > > 
> > > Bit 11 in intel PDC definitions is meant for OS capability to handle
> > > hardware coordination of P-states. In Linux we have always supported
> > > hwardware coordination of P-states. Just let the BIOSes know that we
> > > support it, by setting this bit.
> > > 
> > > Some BIOSes use this bit to choose between hardware or software coordination
> > > and without this change below, BIOSes switch to software coordination, which
> > > is not very optimal in terms of power consumption and extra wakeups from idle.
> > 
> > I can confirm that this fixes the excessive reschedule ipi count on an
> > x60 with the ondemand governor. Can we please get this into 2.6.29?
> 
> And, after that, -stable?
> 

Agreed. This should also go to -stable once it gets into mainline.

Thanks,
Venki

Re: [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Greg KH]

On Wed, Feb 04, 2009 at 12:06:42PM -0800, Pallipadi, Venkatesh wrote:
> On Wed, 2009-02-04 at 11:53 -0800, Henrique de Moraes Holschuh wrote:
> > On Wed, 04 Feb 2009, Jens Axboe wrote:
> > > On Mon, Feb 02 2009, Pallipadi, Venkatesh wrote:
> > > > 
> > > > Bit 11 in intel PDC definitions is meant for OS capability to handle
> > > > hardware coordination of P-states. In Linux we have always supported
> > > > hwardware coordination of P-states. Just let the BIOSes know that we
> > > > support it, by setting this bit.
> > > > 
> > > > Some BIOSes use this bit to choose between hardware or software coordination
> > > > and without this change below, BIOSes switch to software coordination, which
> > > > is not very optimal in terms of power consumption and extra wakeups from idle.
> > > 
> > > I can confirm that this fixes the excessive reschedule ipi count on an
> > > x60 with the ondemand governor. Can we please get this into 2.6.29?
> > 
> > And, after that, -stable?
> > 
> 
> Agreed. This should also go to -stable once it gets into mainline.

Can someone send stable@kernel.org the git commit id when it goes into
Linus's tree?

thanks,

greg k-h

Re: [stable] [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Greg KH]

On Wed, Feb 04, 2009 at 12:40:36PM -0800, Greg KH wrote:
> On Wed, Feb 04, 2009 at 12:06:42PM -0800, Pallipadi, Venkatesh wrote:
> > On Wed, 2009-02-04 at 11:53 -0800, Henrique de Moraes Holschuh wrote:
> > > On Wed, 04 Feb 2009, Jens Axboe wrote:
> > > > On Mon, Feb 02 2009, Pallipadi, Venkatesh wrote:
> > > > > 
> > > > > Bit 11 in intel PDC definitions is meant for OS capability to handle
> > > > > hardware coordination of P-states. In Linux we have always supported
> > > > > hwardware coordination of P-states. Just let the BIOSes know that we
> > > > > support it, by setting this bit.
> > > > > 
> > > > > Some BIOSes use this bit to choose between hardware or software coordination
> > > > > and without this change below, BIOSes switch to software coordination, which
> > > > > is not very optimal in terms of power consumption and extra wakeups from idle.
> > > > 
> > > > I can confirm that this fixes the excessive reschedule ipi count on an
> > > > x60 with the ondemand governor. Can we please get this into 2.6.29?
> > > 
> > > And, after that, -stable?
> > > 
> > 
> > Agreed. This should also go to -stable once it gets into mainline.
> 
> Can someone send stable@kernel.org the git commit id when it goes into
> Linus's tree?

It's d96f94c604453f87fe24154b87e1e9a3a72511f8, I got it now.

thanks,

greg k-h

Re: [PATCH] Enable bit 11 in _PDC to advertise hw coord

[Len Brown]

applied
thanks,
--
Len Brown, Intel Open Source Technology Center

On Mon, 2 Feb 2009, Pallipadi, Venkatesh wrote:

> 
> Bit 11 in intel PDC definitions is meant for OS capability to handle
> hardware coordination of P-states. In Linux we have always supported
> hwardware coordination of P-states. Just let the BIOSes know that we
> support it, by setting this bit.
> 
> Some BIOSes use this bit to choose between hardware or software coordination
> and without this change below, BIOSes switch to software coordination, which
> is not very optimal in terms of power consumption and extra wakeups from idle.
> 
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> 
> ---
>  include/acpi/pdc_intel.h |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux-2.6/include/acpi/pdc_intel.h
> ===================================================================
> --- linux-2.6.orig/include/acpi/pdc_intel.h	2009-01-20 16:11:20.000000000 -0800
> +++ linux-2.6/include/acpi/pdc_intel.h	2009-02-02 10:32:06.000000000 -0800
> @@ -14,6 +14,7 @@
>  #define ACPI_PDC_SMP_T_SWCOORD		(0x0080)
>  #define ACPI_PDC_C_C1_FFH		(0x0100)
>  #define ACPI_PDC_C_C2C3_FFH		(0x0200)
> +#define ACPI_PDC_SMP_P_HWCOORD		(0x0800)
>  
>  #define ACPI_PDC_EST_CAPABILITY_SMP	(ACPI_PDC_SMP_C1PT | \
>  					 ACPI_PDC_C_C1_HALT | \
> @@ -22,6 +23,7 @@
>  #define ACPI_PDC_EST_CAPABILITY_SWSMP	(ACPI_PDC_SMP_C1PT | \
>  					 ACPI_PDC_C_C1_HALT | \
>  					 ACPI_PDC_SMP_P_SWCOORD | \
> +					 ACPI_PDC_SMP_P_HWCOORD | \
>  					 ACPI_PDC_P_FFH)
>  
>  #define ACPI_PDC_C_CAPABILITY_SMP	(ACPI_PDC_SMP_C2C3  | \
> --
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