cpufreq: intel_pstate: Configurable algorithm to get target pstate

Target systems using different cpus have different power and performance
requirements. They may use different algorithms to get the next P-state
based on their power or performance preference.

For example, power-constrained systems may not want to use
high-performance P-states as aggressively as a full-size desktop or a
server platform. A server platform may want to run close to the max to
achieve better performance, while laptop-like systems may prefer
sacrificing performance for longer battery lifes.

For the above reasons, modify intel_pstate to allow the target P-state
selection algorithm to be depend on the CPU ID.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Philippe Longepe <philippe.longepe@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 4d07cbd2b23cfb80ddc40fc0822ce37464991498..ff58029a56e20f4a26a7ce733e3e7ad49487cfd2 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -66,6 +66,7 @@ static inline int ceiling_fp(int32_t x)
 
 struct sample {
        int32_t core_pct_busy;
+       int32_t busy_scaled;
        u64 aperf;
        u64 mperf;
        u64 tsc;
@@ -133,6 +134,7 @@ struct pstate_funcs {
        int (*get_scaling)(void);
        void (*set)(struct cpudata*, int pstate);
        void (*get_vid)(struct cpudata *);
+       int32_t (*get_target_pstate)(struct cpudata *);
 };
 
 struct cpu_defaults {
@@ -140,6 +142,8 @@ struct cpu_defaults {
        struct pstate_funcs funcs;
 };
 
+static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu);
+
 static struct pstate_adjust_policy pid_params;
 static struct pstate_funcs pstate_funcs;
 static int hwp_active;
@@ -738,6 +742,7 @@ static struct cpu_defaults core_params = {
                .get_turbo = core_get_turbo_pstate,
                .get_scaling = core_get_scaling,
                .set = core_set_pstate,
+               .get_target_pstate = get_target_pstate_use_performance,
        },
 };
 
@@ -758,6 +763,7 @@ static struct cpu_defaults silvermont_params = {
                .set = atom_set_pstate,
                .get_scaling = silvermont_get_scaling,
                .get_vid = atom_get_vid,
+               .get_target_pstate = get_target_pstate_use_performance,
        },
 };
 
@@ -778,6 +784,7 @@ static struct cpu_defaults airmont_params = {
                .set = atom_set_pstate,
                .get_scaling = airmont_get_scaling,
                .get_vid = atom_get_vid,
+               .get_target_pstate = get_target_pstate_use_performance,
        },
 };
 
@@ -797,6 +804,7 @@ static struct cpu_defaults knl_params = {
                .get_turbo = knl_get_turbo_pstate,
                .get_scaling = core_get_scaling,
                .set = core_set_pstate,
+               .get_target_pstate = get_target_pstate_use_performance,
        },
 };
 
@@ -922,7 +930,7 @@ static inline void intel_pstate_set_sample_time(struct cpudata *cpu)
        mod_timer_pinned(&cpu->timer, jiffies + delay);
 }
 
-static inline int32_t intel_pstate_get_scaled_busy(struct cpudata *cpu)
+static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
 {
        int32_t core_busy, max_pstate, current_pstate, sample_ratio;
        s64 duration_us;
@@ -960,30 +968,24 @@ static inline int32_t intel_pstate_get_scaled_busy(struct cpudata *cpu)
                core_busy = mul_fp(core_busy, sample_ratio);
        }
 
-       return core_busy;
+       cpu->sample.busy_scaled = core_busy;
+       return cpu->pstate.current_pstate - pid_calc(&cpu->pid, core_busy);
 }
 
 static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
 {
-       int32_t busy_scaled;
-       struct _pid *pid;
-       signed int ctl;
-       int from;
+       int from, target_pstate;
        struct sample *sample;
 
        from = cpu->pstate.current_pstate;
 
-       pid = &cpu->pid;
-       busy_scaled = intel_pstate_get_scaled_busy(cpu);
+       target_pstate = pstate_funcs.get_target_pstate(cpu);
 
-       ctl = pid_calc(pid, busy_scaled);
-
-       /* Negative values of ctl increase the pstate and vice versa */
-       intel_pstate_set_pstate(cpu, cpu->pstate.current_pstate - ctl, true);
+       intel_pstate_set_pstate(cpu, target_pstate, true);
 
        sample = &cpu->sample;
        trace_pstate_sample(fp_toint(sample->core_pct_busy),
-               fp_toint(busy_scaled),
+               fp_toint(sample->busy_scaled),
                from,
                cpu->pstate.current_pstate,
                sample->mperf,
@@ -1237,6 +1239,8 @@ static void copy_cpu_funcs(struct pstate_funcs *funcs)
        pstate_funcs.get_scaling = funcs->get_scaling;
        pstate_funcs.set       = funcs->set;
        pstate_funcs.get_vid   = funcs->get_vid;
+       pstate_funcs.get_target_pstate = funcs->get_target_pstate;
+
 }
 
 #if IS_ENABLED(CONFIG_ACPI)