[PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[Srinivas Pandruvada]

Intel processors support additional software hint called EPB ("Energy
Performance Bias") to guide the hardware heuristic of power management
features to favor increasing dynamic performance or conserve energy
consumption.

Since this EPB hint is processor specific, the same value of hint can
result in different behavior across generations of processors.

commit 4ecc933b7d1f ("x86: intel_epb: Allow model specific normal EPB
value")' introduced capability to update the default power up EPB
based on the CPU model and updated the default EPB to 7 for Alder Lake
mobile CPUs.

The same change is required for other Alder Lake-N and Raptor Lake-P
mobile CPUs as the current default of 6 results in higher uncore power
consumption. This increase in power is related to memory clock
frequency setting based on the EPB value.

Depending on the EPB the minimum memory frequency is set by the
firmware. At EPB = 7, the minimum memory frequency is 1/4th compared to
EPB = 6. This results in significant power saving for idle and
semi-idle workload on a Chrome platform.

For example Change in power and performance from EPB change from 6 to 7
on Alder Lake-N:

Workload    Performance diff (%)    power diff
----------------------------------------------------
VP9 FHD30	0 (FPS)		-218 mw
Google meet	0 (FPS)		-385 mw

This 200+ mw power saving is very significant for mobile platform for
battery life and thermal reasons.

But as the workload demands more memory bandwidth, the memory frequency
will be increased very fast. There is no power savings for such busy
workloads.

For example:

Workload		Performance diff (%) from EPB 6 to 7
-------------------------------------------------------
Speedometer 2.0		-0.8
WebGL Aquarium 10K
Fish    		-0.5
Unity 3D 2018		0.2
WebXPRT3		-0.5

There are run to run variations for performance scores for
such busy workloads. So the difference is not significant.

Add a new define ENERGY_PERF_BIAS_NORMAL_POWERSAVE for EPB 7
and use it for Alder Lake-N and Raptor Lake-P mobile CPUs.

This modification is done originally by
Jeremy Compostella <jeremy.compostella@intel.com>.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 arch/x86/include/asm/msr-index.h | 1 +
 arch/x86/kernel/cpu/intel_epb.c  | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 10ac52705892..a3eb4d3e70b8 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -796,6 +796,7 @@
 #define ENERGY_PERF_BIAS_PERFORMANCE		0
 #define ENERGY_PERF_BIAS_BALANCE_PERFORMANCE	4
 #define ENERGY_PERF_BIAS_NORMAL			6
+#define ENERGY_PERF_BIAS_NORMAL_POWERSAVE	7
 #define ENERGY_PERF_BIAS_BALANCE_POWERSAVE	8
 #define ENERGY_PERF_BIAS_POWERSAVE		15
 
diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
index fbaf12e43f41..3b8476158236 100644
--- a/arch/x86/kernel/cpu/intel_epb.c
+++ b/arch/x86/kernel/cpu/intel_epb.c
@@ -204,7 +204,12 @@ static int intel_epb_offline(unsigned int cpu)
 }
 
 static const struct x86_cpu_id intel_epb_normal[] = {
-	X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L, 7),
+	X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L,
+				   ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
+	X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_N,
+				   ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
+	X86_MATCH_INTEL_FAM6_MODEL(RAPTORLAKE_P,
+				   ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
 	{}
 };
 
-- 
2.31.1

Re: [PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[Dave Hansen]

So, the tl;dr on this is:

	The EPB setting is fundamentally a classic power vs. performance
	knob.  This change helps power a bunch (200+mw) while having a
	negligible performance impact (<1% if that), so it's a great
	trade-off.

Right?

Re: [PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[srinivas pandruvada]

On Thu, 2022-10-27 at 15:30 -0700, Dave Hansen wrote:
> So, the tl;dr on this is:
> 
>         The EPB setting is fundamentally a classic power vs.
> performance
>         knob.  This change helps power a bunch (200+mw) while having
> a
>         negligible performance impact (<1% if that), so it's a great
>         trade-off.
> 
> Right?
Yes.
We already using EPB 7 on other AlderLake Mobiles.

Thanks,
Srinivas

Re: [PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[Rafael J. Wysocki]

On Fri, Oct 28, 2022 at 12:01 AM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> Intel processors support additional software hint called EPB ("Energy
> Performance Bias") to guide the hardware heuristic of power management
> features to favor increasing dynamic performance or conserve energy
> consumption.
>
> Since this EPB hint is processor specific, the same value of hint can
> result in different behavior across generations of processors.
>
> commit 4ecc933b7d1f ("x86: intel_epb: Allow model specific normal EPB
> value")' introduced capability to update the default power up EPB
> based on the CPU model and updated the default EPB to 7 for Alder Lake
> mobile CPUs.
>
> The same change is required for other Alder Lake-N and Raptor Lake-P
> mobile CPUs as the current default of 6 results in higher uncore power
> consumption. This increase in power is related to memory clock
> frequency setting based on the EPB value.
>
> Depending on the EPB the minimum memory frequency is set by the
> firmware. At EPB = 7, the minimum memory frequency is 1/4th compared to
> EPB = 6. This results in significant power saving for idle and
> semi-idle workload on a Chrome platform.
>
> For example Change in power and performance from EPB change from 6 to 7
> on Alder Lake-N:
>
> Workload    Performance diff (%)    power diff
> ----------------------------------------------------
> VP9 FHD30       0 (FPS)         -218 mw
> Google meet     0 (FPS)         -385 mw
>
> This 200+ mw power saving is very significant for mobile platform for
> battery life and thermal reasons.
>
> But as the workload demands more memory bandwidth, the memory frequency
> will be increased very fast. There is no power savings for such busy
> workloads.
>
> For example:
>
> Workload                Performance diff (%) from EPB 6 to 7
> -------------------------------------------------------
> Speedometer 2.0         -0.8
> WebGL Aquarium 10K
> Fish                    -0.5
> Unity 3D 2018           0.2
> WebXPRT3                -0.5
>
> There are run to run variations for performance scores for
> such busy workloads. So the difference is not significant.
>
> Add a new define ENERGY_PERF_BIAS_NORMAL_POWERSAVE for EPB 7
> and use it for Alder Lake-N and Raptor Lake-P mobile CPUs.
>
> This modification is done originally by
> Jeremy Compostella <jeremy.compostella@intel.com>.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  arch/x86/include/asm/msr-index.h | 1 +
>  arch/x86/kernel/cpu/intel_epb.c  | 7 ++++++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index 10ac52705892..a3eb4d3e70b8 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -796,6 +796,7 @@
>  #define ENERGY_PERF_BIAS_PERFORMANCE           0
>  #define ENERGY_PERF_BIAS_BALANCE_PERFORMANCE   4
>  #define ENERGY_PERF_BIAS_NORMAL                        6
> +#define ENERGY_PERF_BIAS_NORMAL_POWERSAVE      7
>  #define ENERGY_PERF_BIAS_BALANCE_POWERSAVE     8
>  #define ENERGY_PERF_BIAS_POWERSAVE             15
>
> diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
> index fbaf12e43f41..3b8476158236 100644
> --- a/arch/x86/kernel/cpu/intel_epb.c
> +++ b/arch/x86/kernel/cpu/intel_epb.c
> @@ -204,7 +204,12 @@ static int intel_epb_offline(unsigned int cpu)
>  }
>
>  static const struct x86_cpu_id intel_epb_normal[] = {
> -       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L, 7),
> +       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L,
> +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
> +       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_N,
> +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
> +       X86_MATCH_INTEL_FAM6_MODEL(RAPTORLAKE_P,
> +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
>         {}
>  };
>
> --
> 2.31.1
>

Re: [PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[Rafael J. Wysocki]

On Fri, Oct 28, 2022 at 5:24 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Fri, Oct 28, 2022 at 12:01 AM Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> >
> > Intel processors support additional software hint called EPB ("Energy
> > Performance Bias") to guide the hardware heuristic of power management
> > features to favor increasing dynamic performance or conserve energy
> > consumption.
> >
> > Since this EPB hint is processor specific, the same value of hint can
> > result in different behavior across generations of processors.
> >
> > commit 4ecc933b7d1f ("x86: intel_epb: Allow model specific normal EPB
> > value")' introduced capability to update the default power up EPB
> > based on the CPU model and updated the default EPB to 7 for Alder Lake
> > mobile CPUs.
> >
> > The same change is required for other Alder Lake-N and Raptor Lake-P
> > mobile CPUs as the current default of 6 results in higher uncore power
> > consumption. This increase in power is related to memory clock
> > frequency setting based on the EPB value.
> >
> > Depending on the EPB the minimum memory frequency is set by the
> > firmware. At EPB = 7, the minimum memory frequency is 1/4th compared to
> > EPB = 6. This results in significant power saving for idle and
> > semi-idle workload on a Chrome platform.
> >
> > For example Change in power and performance from EPB change from 6 to 7
> > on Alder Lake-N:
> >
> > Workload    Performance diff (%)    power diff
> > ----------------------------------------------------
> > VP9 FHD30       0 (FPS)         -218 mw
> > Google meet     0 (FPS)         -385 mw
> >
> > This 200+ mw power saving is very significant for mobile platform for
> > battery life and thermal reasons.
> >
> > But as the workload demands more memory bandwidth, the memory frequency
> > will be increased very fast. There is no power savings for such busy
> > workloads.
> >
> > For example:
> >
> > Workload                Performance diff (%) from EPB 6 to 7
> > -------------------------------------------------------
> > Speedometer 2.0         -0.8
> > WebGL Aquarium 10K
> > Fish                    -0.5
> > Unity 3D 2018           0.2
> > WebXPRT3                -0.5
> >
> > There are run to run variations for performance scores for
> > such busy workloads. So the difference is not significant.
> >
> > Add a new define ENERGY_PERF_BIAS_NORMAL_POWERSAVE for EPB 7
> > and use it for Alder Lake-N and Raptor Lake-P mobile CPUs.
> >
> > This modification is done originally by
> > Jeremy Compostella <jeremy.compostella@intel.com>.
> >
> > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

I'm wondering if there are any plans to pick up this one into the x86
tree?  If not, I can take care of it.

> > ---
> >  arch/x86/include/asm/msr-index.h | 1 +
> >  arch/x86/kernel/cpu/intel_epb.c  | 7 ++++++-
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> > index 10ac52705892..a3eb4d3e70b8 100644
> > --- a/arch/x86/include/asm/msr-index.h
> > +++ b/arch/x86/include/asm/msr-index.h
> > @@ -796,6 +796,7 @@
> >  #define ENERGY_PERF_BIAS_PERFORMANCE           0
> >  #define ENERGY_PERF_BIAS_BALANCE_PERFORMANCE   4
> >  #define ENERGY_PERF_BIAS_NORMAL                        6
> > +#define ENERGY_PERF_BIAS_NORMAL_POWERSAVE      7
> >  #define ENERGY_PERF_BIAS_BALANCE_POWERSAVE     8
> >  #define ENERGY_PERF_BIAS_POWERSAVE             15
> >
> > diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
> > index fbaf12e43f41..3b8476158236 100644
> > --- a/arch/x86/kernel/cpu/intel_epb.c
> > +++ b/arch/x86/kernel/cpu/intel_epb.c
> > @@ -204,7 +204,12 @@ static int intel_epb_offline(unsigned int cpu)
> >  }
> >
> >  static const struct x86_cpu_id intel_epb_normal[] = {
> > -       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L, 7),
> > +       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L,
> > +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
> > +       X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_N,
> > +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
> > +       X86_MATCH_INTEL_FAM6_MODEL(RAPTORLAKE_P,
> > +                                  ENERGY_PERF_BIAS_NORMAL_POWERSAVE),
> >         {}
> >  };
> >
> > --
> > 2.31.1
> >

Re: [PATCH] x86: intel_epb: Set Alder Lake N and Raptor Lake P normal EPB

[Dave Hansen]

On 11/3/22 11:25, Rafael J. Wysocki wrote:
> I'm wondering if there are any plans to pick up this one into the x86
> tree?  If not, I can take care of it.

I'll bump it up to the front of the queue. :)

Thanks for the reminder.