Re: [PATCH 3/5] cpufreq: intel-pstate: Use separate max pstate for scaling

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Thu, 2015-08-27 at 01:14 +0200, Rafael J. Wysocki wrote:
> On Wednesday, August 26, 2015 01:32:39 PM Srinivas Pandruvada wrote:
> > Systems with configurable TDP have multiple max non turbo p state. 
> > Intel
> > P state uses max non turbo P state for scaling. But using the real 
> > max
> > non turbo p state causes underestimation of next P state. So using
> > the physical max non turbo P state as before for scaling.
> 
> What does "physical" mean here?
That is the max non turbo p state a particular processor family can
reach. For example a Broadwell client processor, the max non turbo P
state can be up to 0x17. This I am calling physical. May be not a good
choice of word?
OEMs may not want the non turbo P state to be this high and can reduce
by changing turbo activation ratio.

Thanks,
Srinivas
> > Signed-off-by: Srinivas Pandruvada <
> > srinivas.pandruvada@linux.intel.com>
> > ---
> >  drivers/cpufreq/intel_pstate.c | 20 ++++++++++++++++++--
> >  1 file changed, 18 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/intel_pstate.c 
> > b/drivers/cpufreq/intel_pstate.c
> > index 2641102..a349462 100644
> > --- a/drivers/cpufreq/intel_pstate.c
> > +++ b/drivers/cpufreq/intel_pstate.c
> > @@ -77,6 +77,7 @@ struct pstate_data {
> >  	int	current_pstate;
> >  	int	min_pstate;
> >  	int	max_pstate;
> > +	int	max_pstate_physical;
> >  	int	scaling;
> >  	int	turbo_pstate;
> >  	u64	turbo_ratio_limit;
> > @@ -127,6 +128,7 @@ struct pstate_adjust_policy {
> >  
> >  struct pstate_funcs {
> >  	int (*get_max)(void);
> > +	int (*get_max_physical)(void);
> >  	int (*get_min)(void);
> >  	int (*get_turbo)(void);
> >  	int (*get_scaling)(void);
> > @@ -599,6 +601,14 @@ static int core_get_min_pstate(void)
> >  	return (value >> 40) & 0xFF;
> >  }
> >  
> > +static int core_get_max_pstate_physical(void)
> > +{
> > +	u64 value;
> > +
> > +	rdmsrl(MSR_PLATFORM_INFO, value);
> > +	return (value >> 8) & 0xFF;
> > +}
> > +
> >  static int core_get_max_pstate(void)
> >  {
> >  	u64 tar;
> > @@ -741,6 +751,7 @@ static struct cpu_defaults core_params = {
> >  	},
> >  	.funcs = {
> >  		.get_max = core_get_max_pstate,
> > +		.get_max_physical = core_get_max_pstate_physical,
> >  		.get_min = core_get_min_pstate,
> >  		.get_turbo = core_get_turbo_pstate,
> >  		.get_scaling = core_get_scaling,
> > @@ -761,6 +772,7 @@ static struct cpu_defaults byt_params = {
> >  	},
> >  	.funcs = {
> >  		.get_max = byt_get_max_pstate,
> > +		.get_max_physical = byt_get_max_pstate,
> >  		.get_min = byt_get_min_pstate,
> >  		.get_turbo = byt_get_turbo_pstate,
> >  		.set = byt_set_pstate,
> > @@ -780,6 +792,7 @@ static struct cpu_defaults knl_params = {
> >  	},
> >  	.funcs = {
> >  		.get_max = core_get_max_pstate,
> > +		.get_max_physical = core_get_max_pstate_physical,
> >  		.get_min = core_get_min_pstate,
> >  		.get_turbo = knl_get_turbo_pstate,
> >  		.set = core_set_pstate,
> > @@ -833,6 +846,7 @@ static void intel_pstate_get_cpu_pstates(struct 
> > cpudata *cpu)
> >  {
> >  	cpu->pstate.min_pstate = pstate_funcs.get_min();
> >  	cpu->pstate.max_pstate = pstate_funcs.get_max();
> > +	cpu->pstate.max_pstate_physical = 
> > pstate_funcs.get_max_physical();
> >  	cpu->pstate.turbo_pstate = pstate_funcs.get_turbo();
> >  	cpu->pstate.scaling = pstate_funcs.get_scaling();
> >  	if (pstate_funcs.get_turbo_ratio_limit &&
> > @@ -854,7 +868,8 @@ static inline void 
> > intel_pstate_calc_busy(struct cpudata *cpu)
> >  
> >  	sample->freq = fp_toint(
> >  		mul_fp(int_tofp(
> > -			cpu->pstate.max_pstate * cpu
> > ->pstate.scaling / 100),
> > +			cpu->pstate.max_pstate_physical *
> > +			cpu->pstate.scaling / 100),
> >  			core_pct));
> >  
> >  	sample->core_pct_busy = (int32_t)core_pct;
> > @@ -922,7 +937,7 @@ static inline int32_t 
> > intel_pstate_get_scaled_busy(struct cpudata *cpu)
> >  	 * specified pstate.
> >  	 */
> >  	core_busy = cpu->sample.core_pct_busy;
> > -	max_pstate = int_tofp(cpu->pstate.max_pstate);
> > +	max_pstate = int_tofp(cpu->pstate.max_pstate_physical);
> >  	current_pstate = int_tofp(cpu->pstate.current_pstate);
> >  	core_busy = mul_fp(core_busy, div_fp(max_pstate, 
> > current_pstate));
> >  
> > @@ -1215,6 +1230,7 @@ static void copy_pid_params(struct 
> > pstate_adjust_policy *policy)
> >  static void copy_cpu_funcs(struct pstate_funcs *funcs)
> >  {
> >  	pstate_funcs.get_max   = funcs->get_max;
> > +	pstate_funcs.get_max_physical = funcs->get_max_physical;
> >  	pstate_funcs.get_min   = funcs->get_min;
> >  	pstate_funcs.get_turbo = funcs->get_turbo;
> >  	pstate_funcs.get_scaling = funcs->get_scaling;
> > 
>