cpufreq: intel_pstate: Assorted cleanups

PATCH In review Rafael J. Wysocki 2 participants 7 messages Jan 7, 2021 – Jan 8, 2021

Subsystems (2)

CPU frequency scaling framework Intel pstate driver

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Rafael J. Wysocki

author

2021-01-07 18:45 UTC #0 lore raw

cover cpufreq: intel_pstate: Assorted cleanups

Hi,

These three patches clean up intel_pstate a bit:

[1/3] makes it always use READ_ONCE() for reading hwp_cap_cached [2/3] changes the first argument of intel_pstate_get_hwp_max() [3/3] renames to functions (to avoid possible confusion).

Please see patch changelogs for details.

Thanks!

Rafael J. Wysocki

author

2021-01-07 18:45 UTC #1 lore raw

PATCH 1/3 cpufreq: intel_pstate: Always read hwp_cap_cached with READ_ONCE()

From: Rafael J. Wysocki <[email protected]>

Because intel_pstate_get_hwp_max() which updates hwp_cap_cached may run in parallel with the readers of it, annotate all of the read accesses to it with READ_ONCE().

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/cpufreq/intel_pstate.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

drivers/cpufreq/intel_pstate.c +7 -6

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
@@ -914,7 +914,7 @@ static void intel_pstate_hwp_offline(str
 	}
 
 	value &= ~GENMASK_ULL(31, 0);
-	min_perf = HWP_LOWEST_PERF(cpu->hwp_cap_cached);
+	min_perf = HWP_LOWEST_PERF(READ_ONCE(cpu->hwp_cap_cached));
 
 	/* Set hwp_max = hwp_min */
 	value |= HWP_MAX_PERF(min_perf);

@@ -1750,6 +1750,7 @@ static int hwp_boost_hold_time_ns = 3 *
 static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu)
 {
 	u64 hwp_req = READ_ONCE(cpu->hwp_req_cached);
+	u64 hwp_cap = READ_ONCE(cpu->hwp_cap_cached);
 	u32 max_limit = (hwp_req & 0xff00) >> 8;
 	u32 min_limit = (hwp_req & 0xff);
 	u32 boost_level1;

@@ -1776,14 +1777,14 @@ static inline void intel_pstate_hwp_boos
 		cpu->hwp_boost_min = min_limit;
 
 	/* level at half way mark between min and guranteed */
-	boost_level1 = (HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) + min_limit) >> 1;
+	boost_level1 = (HWP_GUARANTEED_PERF(hwp_cap) + min_limit) >> 1;
 
 	if (cpu->hwp_boost_min < boost_level1)
 		cpu->hwp_boost_min = boost_level1;
-	else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(cpu->hwp_cap_cached))
-		cpu->hwp_boost_min = HWP_GUARANTEED_PERF(cpu->hwp_cap_cached);
-	else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) &&
-		 max_limit != HWP_GUARANTEED_PERF(cpu->hwp_cap_cached))
+	else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(hwp_cap))
+		cpu->hwp_boost_min = HWP_GUARANTEED_PERF(hwp_cap);
+	else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(hwp_cap) &&
+		 max_limit != HWP_GUARANTEED_PERF(hwp_cap))
 		cpu->hwp_boost_min = max_limit;
 	else
 		return;

Chen Yu

Tested-by on v1 1/3

2021-01-08 07:00 UTC #2 lore raw

Re: [PATCH v1 1/3] cpufreq: intel_pstate: Always read hwp_cap_cached with READ_ONCE()

Quoted 7 lines · Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>
Because intel_pstate_get_hwp_max() which updates hwp_cap_cached may run in parallel with the readers of it, annotate all of the read accesses to it with READ_ONCE().
Signed-off-by Rafael J. Wysocki <[email protected]>

Tested-by Chen Yu <[email protected]>

thanks,
Chenyu

Rafael J. Wysocki

author

2021-01-07 18:45 UTC #3 lore raw

PATCH 2/3 cpufreq: intel_pstate: Change intel_pstate_get_hwp_max() argument

In reply to Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>

All of the callers of intel_pstate_get_hwp_max() access the struct cpudata object that corresponds to the given CPU already and the function itself needs to access that object (in order to update hwp_cap_cached), so modify the code to pass a struct cpudata pointer to it instead of the CPU number.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/cpufreq/intel_pstate.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

drivers/cpufreq/intel_pstate.c +8 -8

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
@@ -819,13 +819,13 @@ static struct freq_attr *hwp_cpufreq_att
 	NULL,
 };
 
-static void intel_pstate_get_hwp_max(unsigned int cpu, int *phy_max,
+static void intel_pstate_get_hwp_max(struct cpudata *cpu, int *phy_max,
 				     int *current_max)
 {
 	u64 cap;
 
-	rdmsrl_on_cpu(cpu, MSR_HWP_CAPABILITIES, &cap);
-	WRITE_ONCE(all_cpu_data[cpu]->hwp_cap_cached, cap);
+	rdmsrl_on_cpu(cpu->cpu, MSR_HWP_CAPABILITIES, &cap);
+	WRITE_ONCE(cpu->hwp_cap_cached, cap);
 	if (global.no_turbo || global.turbo_disabled)
 		*current_max = HWP_GUARANTEED_PERF(cap);
 	else

@@ -1213,7 +1213,7 @@ static void update_qos_request(enum freq
 			continue;
 
 		if (hwp_active)
-			intel_pstate_get_hwp_max(i, &turbo_max, &max_state);
+			intel_pstate_get_hwp_max(cpu, &turbo_max, &max_state);
 		else
 			turbo_max = cpu->pstate.turbo_pstate;

@@ -1723,7 +1723,7 @@ static void intel_pstate_get_cpu_pstates
 	if (hwp_active && !hwp_mode_bdw) {
 		unsigned int phy_max, current_max;
 
-		intel_pstate_get_hwp_max(cpu->cpu, &phy_max, &current_max);
+		intel_pstate_get_hwp_max(cpu, &phy_max, &current_max);
 		cpu->pstate.turbo_freq = phy_max * cpu->pstate.scaling;
 		cpu->pstate.turbo_pstate = phy_max;
 	} else {

@@ -2208,7 +2208,7 @@ static void intel_pstate_update_perf_lim
 	 * rather than pure ratios.
 	 */
 	if (hwp_active) {
-		intel_pstate_get_hwp_max(cpu->cpu, &turbo_max, &max_state);
+		intel_pstate_get_hwp_max(cpu, &turbo_max, &max_state);
 	} else {
 		max_state = global.no_turbo || global.turbo_disabled ?
 			cpu->pstate.max_pstate : cpu->pstate.turbo_pstate;

@@ -2323,7 +2323,7 @@ static void intel_pstate_verify_cpu_poli
 	if (hwp_active) {
 		int max_state, turbo_max;
 
-		intel_pstate_get_hwp_max(cpu->cpu, &turbo_max, &max_state);
+		intel_pstate_get_hwp_max(cpu, &turbo_max, &max_state);
 		max_freq = max_state * cpu->pstate.scaling;
 	} else {
 		max_freq = intel_pstate_get_max_freq(cpu);

@@ -2710,7 +2710,7 @@ static int intel_cpufreq_cpu_init(struct
 	if (hwp_active) {
 		u64 value;
 
-		intel_pstate_get_hwp_max(policy->cpu, &turbo_max, &max_state);
+		intel_pstate_get_hwp_max(cpu, &turbo_max, &max_state);
 		policy->transition_delay_us = INTEL_CPUFREQ_TRANSITION_DELAY_HWP;
 		rdmsrl_on_cpu(cpu->cpu, MSR_HWP_REQUEST, &value);
 		WRITE_ONCE(cpu->hwp_req_cached, value);

Chen Yu

Tested-by on v1 2/3

2021-01-08 06:59 UTC #4 lore raw

Re: [PATCH v1 2/3] cpufreq: intel_pstate: Change intel_pstate_get_hwp_max() argument

Quoted 9 lines · Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>
All of the callers of intel_pstate_get_hwp_max() access the struct cpudata object that corresponds to the given CPU already and the function itself needs to access that object (in order to update hwp_cap_cached), so modify the code to pass a struct cpudata pointer to it instead of the CPU number.
Signed-off-by Rafael J. Wysocki <[email protected]>

Tested-by Chen Yu <[email protected]>

thanks,
Chenyu

Rafael J. Wysocki

author

2021-01-07 18:45 UTC #5 lore raw

PATCH 3/3 cpufreq: intel_pstate: Rename two functions

In reply to Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>

Rename intel_cpufreq_adjust_hwp() and intel_cpufreq_adjust_perf_ctl() to intel_cpufreq_hwp_update() and intel_cpufreq_perf_ctl_update(), respectively, to avoid possible confusion with the ->adjist_perf() callback function, intel_cpufreq_adjust_perf().

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/cpufreq/intel_pstate.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

drivers/cpufreq/intel_pstate.c +5 -5

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
@@ -2527,7 +2527,7 @@ static void intel_cpufreq_trace(struct c
 		fp_toint(cpu->iowait_boost * 100));
 }
 
-static void intel_cpufreq_adjust_hwp(struct cpudata *cpu, u32 min, u32 max,
+static void intel_cpufreq_hwp_update(struct cpudata *cpu, u32 min, u32 max,
 				     u32 desired, bool fast_switch)
 {
 	u64 prev = READ_ONCE(cpu->hwp_req_cached), value = prev;

@@ -2551,7 +2551,7 @@ static void intel_cpufreq_adjust_hwp(str
 		wrmsrl_on_cpu(cpu->cpu, MSR_HWP_REQUEST, value);
 }
 
-static void intel_cpufreq_adjust_perf_ctl(struct cpudata *cpu,
+static void intel_cpufreq_perf_ctl_update(struct cpudata *cpu,
 					  u32 target_pstate, bool fast_switch)
 {
 	if (fast_switch)

@@ -2573,10 +2573,10 @@ static int intel_cpufreq_update_pstate(s
 		int max_pstate = policy->strict_target ?
 					target_pstate : cpu->max_perf_ratio;
 
-		intel_cpufreq_adjust_hwp(cpu, target_pstate, max_pstate, 0,
+		intel_cpufreq_hwp_update(cpu, target_pstate, max_pstate, 0,
 					 fast_switch);
 	} else if (target_pstate != old_pstate) {
-		intel_cpufreq_adjust_perf_ctl(cpu, target_pstate, fast_switch);
+		intel_cpufreq_perf_ctl_update(cpu, target_pstate, fast_switch);
 	}
 
 	cpu->pstate.current_pstate = target_pstate;

@@ -2674,7 +2674,7 @@ static void intel_cpufreq_adjust_perf(un
 
 	target_pstate = clamp_t(int, target_pstate, min_pstate, max_pstate);
 
-	intel_cpufreq_adjust_hwp(cpu, min_pstate, max_pstate, target_pstate, true);
+	intel_cpufreq_hwp_update(cpu, min_pstate, max_pstate, target_pstate, true);
 
 	cpu->pstate.current_pstate = target_pstate;
 	intel_cpufreq_trace(cpu, INTEL_PSTATE_TRACE_FAST_SWITCH, old_pstate);

Chen Yu

Tested-by on v1 3/3

2021-01-08 06:58 UTC #6 lore raw

Re: [PATCH v1 3/3] cpufreq: intel_pstate: Rename two functions

Quoted 9 lines · Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>
Rename intel_cpufreq_adjust_hwp() and intel_cpufreq_adjust_perf_ctl() to intel_cpufreq_hwp_update() and intel_cpufreq_perf_ctl_update(), respectively, to avoid possible confusion with the ->adjist_perf() callback function, intel_cpufreq_adjust_perf().
Signed-off-by Rafael J. Wysocki <[email protected]>
---

Tested-by Chen Yu <[email protected]>