[PATCH v2] cpufreq, intel_pstate, Fix intel_pstate powersave min_perf_pct value

From: Prarit Bhargava
Date: Thu Oct 15 2015 - 07:34:26 EST

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Rafael, as requested ...

[v2]: rebased on
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git bleeding-edge

^^^ prolly doesn't need to be in the commit log

P.

---8<---

On systems that initialize the intel_pstate driver with the performance
governor, and then switch to the powersave governor will not transition to
lower cpu frequencies until /sys/devices/system/cpu/intel_pstate/min_perf_pct
is set to a low value.

The behavior of governor switching changed after commit a04759924e25
("[cpufreq] intel_pstate: honor user space min_perf_pct override on
resume"). The commit introduced tracking of performance percentage
changes via sysfs in order to restore userspace changes during
suspend/resume. The problem occurs because the global values of the newly
introduced max_sysfs_pct and min_sysfs_pct are not lowered on the governor
change and this causes the powersave governor to inherit the performance
governor's settings.

A simple change would have been to reset max_sysfs_pct to 100 and
min_sysfs_pct to 0 on a governor change, which fixes the problem with
governor switching. However, since we cannot break userspace[1] the fix
is now to give each governor its own limits storage area so that governor
specific changes are tracked.

I successfully tested this by booting with both the performance governor
and the powersave governor by default, and switching between the two
governors (while monitoring /sys/devices/system/cpu/intel_pstate/ values,
and looking at the output of cpupower frequency-info). Suspend/Resume
testing was performed by Doug Smythies.

[1] Systems which suspend/resume using the unmaintained pm-utils package
will always transition to the performance governor before the suspend and
after the resume. This means a system using the powersave governor will
go from powersave to performance, then suspend/resume, performance to
powersave. The simple change during governor changes would have been
overwritten when the governor changed before and after the suspend/resume.
I have submitted https://bugzilla.redhat.com/show_bug.cgi?id=1271225
against Fedora to remove the 94cpufreq file that causes the problem. It
should be noted that pm-utils is obsoleted with newer versions of systemd.

Cc: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: Doug Smythies <dsmythies@xxxxxxxxx>
Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
---
drivers/cpufreq/intel_pstate.c | 142 ++++++++++++++++++++++++-----------------
1 file changed, 85 insertions(+), 57 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index c568226..cde38c8 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -167,7 +167,20 @@ struct perf_limits {
int min_perf_ctl;
};

-static struct perf_limits limits = {
+static struct perf_limits performance_limits = {
+ .no_turbo = 0,
+ .turbo_disabled = 0,
+ .max_perf_pct = 100,
+ .max_perf = int_tofp(1),
+ .min_perf_pct = 100,
+ .min_perf = int_tofp(1),
+ .max_policy_pct = 100,
+ .max_sysfs_pct = 100,
+ .min_policy_pct = 0,
+ .min_sysfs_pct = 0,
+};
+
+static struct perf_limits powersave_limits = {
.no_turbo = 0,
.turbo_disabled = 0,
.max_perf_pct = 100,
@@ -182,6 +195,12 @@ static struct perf_limits limits = {
.min_perf_ctl = 0,
};

+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE
+static struct perf_limits *limits = &performance_limits;
+#else
+static struct perf_limits *limits = &powersave_limits;
+#endif
+
#if IS_ENABLED(CONFIG_ACPI)
/*
* The max target pstate ratio is a 8 bit value in both PLATFORM_INFO MSR and
@@ -256,7 +275,7 @@ static int intel_pstate_init_perf_limits(struct cpufreq_policy *policy)
if (turbo_pss_ctl <= cpu->pstate.max_pstate &&
turbo_pss_ctl > cpu->pstate.min_pstate) {
pr_debug("intel_pstate: no turbo range exists in _PSS\n");
- limits.no_turbo = limits.turbo_disabled = 1;
+ limits->no_turbo = limits->turbo_disabled = 1;
cpu->pstate.turbo_pstate = cpu->pstate.max_pstate;
turbo_absent = true;
}
@@ -415,7 +434,7 @@ static inline void update_turbo_state(void)

cpu = all_cpu_data[0];
rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
- limits.turbo_disabled =
+ limits->turbo_disabled =
(misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE ||
cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
}
@@ -434,14 +453,14 @@ static void intel_pstate_hwp_set(void)

for_each_online_cpu(cpu) {
rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
- adj_range = limits.min_perf_pct * range / 100;
+ adj_range = limits->min_perf_pct * range / 100;
min = hw_min + adj_range;
value &= ~HWP_MIN_PERF(~0L);
value |= HWP_MIN_PERF(min);

- adj_range = limits.max_perf_pct * range / 100;
+ adj_range = limits->max_perf_pct * range / 100;
max = hw_min + adj_range;
- if (limits.no_turbo) {
+ if (limits->no_turbo) {
hw_max = HWP_GUARANTEED_PERF(cap);
if (hw_max < max)
max = hw_max;
@@ -510,7 +529,7 @@ static void __init intel_pstate_debug_expose_params(void)
static ssize_t show_##file_name \
(struct kobject *kobj, struct attribute *attr, char *buf) \
{ \
- return sprintf(buf, "%u\n", limits.object); \
+ return sprintf(buf, "%u\n", limits->object); \
}

static ssize_t show_turbo_pct(struct kobject *kobj,
@@ -546,10 +565,10 @@ static ssize_t show_no_turbo(struct kobject *kobj,
ssize_t ret;

update_turbo_state();
- if (limits.turbo_disabled)
- ret = sprintf(buf, "%u\n", limits.turbo_disabled);
+ if (limits->turbo_disabled)
+ ret = sprintf(buf, "%u\n", limits->turbo_disabled);
else
- ret = sprintf(buf, "%u\n", limits.no_turbo);
+ ret = sprintf(buf, "%u\n", limits->no_turbo);

return ret;
}
@@ -565,12 +584,12 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
return -EINVAL;

update_turbo_state();
- if (limits.turbo_disabled) {
+ if (limits->turbo_disabled) {
pr_warn("intel_pstate: Turbo disabled by BIOS or unavailable on processor\n");
return -EPERM;
}

- limits.no_turbo = clamp_t(int, input, 0, 1);
+ limits->no_turbo = clamp_t(int, input, 0, 1);

if (hwp_active)
intel_pstate_hwp_set();
@@ -588,11 +607,15 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
if (ret != 1)
return -EINVAL;

- limits.max_sysfs_pct = clamp_t(int, input, 0 , 100);
- limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
- limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
- limits.max_perf_pct = max(limits.min_perf_pct, limits.max_perf_pct);
- limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
+ limits->max_sysfs_pct = clamp_t(int, input, 0 , 100);
+ limits->max_perf_pct = min(limits->max_policy_pct,
+ limits->max_sysfs_pct);
+ limits->max_perf_pct = max(limits->min_policy_pct,
+ limits->max_perf_pct);
+ limits->max_perf_pct = max(limits->min_perf_pct,
+ limits->max_perf_pct);
+ limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
+ int_tofp(100));

if (hwp_active)
intel_pstate_hwp_set();
@@ -609,11 +632,15 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
if (ret != 1)
return -EINVAL;

- limits.min_sysfs_pct = clamp_t(int, input, 0 , 100);
- limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
- limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
- limits.min_perf_pct = min(limits.max_perf_pct, limits.min_perf_pct);
- limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
+ limits->min_sysfs_pct = clamp_t(int, input, 0 , 100);
+ limits->min_perf_pct = max(limits->min_policy_pct,
+ limits->min_sysfs_pct);
+ limits->min_perf_pct = min(limits->max_policy_pct,
+ limits->min_perf_pct);
+ limits->min_perf_pct = min(limits->max_perf_pct,
+ limits->min_perf_pct);
+ limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
+ int_tofp(100));

if (hwp_active)
intel_pstate_hwp_set();
@@ -693,7 +720,7 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)
u32 vid;

val = (u64)pstate << 8;
- if (limits.no_turbo && !limits.turbo_disabled)
+ if (limits->no_turbo && !limits->turbo_disabled)
val |= (u64)1 << 32;

vid_fp = cpudata->vid.min + mul_fp(
@@ -822,7 +849,7 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
u64 val;

val = (u64)pstate << 8;
- if (limits.no_turbo && !limits.turbo_disabled)
+ if (limits->no_turbo && !limits->turbo_disabled)
val |= (u64)1 << 32;

wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
@@ -905,7 +932,7 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
int max_perf_adj;
int min_perf;

- if (limits.no_turbo || limits.turbo_disabled)
+ if (limits->no_turbo || limits->turbo_disabled)
max_perf = cpu->pstate.max_pstate;

/*
@@ -913,21 +940,21 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
* policy, or by cpu specific default values determined through
* experimentation.
*/
- if (limits.max_perf_ctl && limits.max_sysfs_pct >=
- limits.max_policy_pct) {
- *max = limits.max_perf_ctl;
+ if (limits->max_perf_ctl && limits->max_sysfs_pct >=
+ limits->max_policy_pct) {
+ *max = limits->max_perf_ctl;
} else {
max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf),
- limits.max_perf));
+ limits->max_perf));
*max = clamp_t(int, max_perf_adj, cpu->pstate.min_pstate,
cpu->pstate.turbo_pstate);
}

- if (limits.min_perf_ctl) {
- *min = limits.min_perf_ctl;
+ if (limits->min_perf_ctl) {
+ *min = limits->min_perf_ctl;
} else {
min_perf = fp_toint(mul_fp(int_tofp(max_perf),
- limits.min_perf));
+ limits->min_perf));
*min = clamp_t(int, min_perf, cpu->pstate.min_pstate, max_perf);
}
}
@@ -1210,34 +1237,35 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)

if (policy->policy == CPUFREQ_POLICY_PERFORMANCE &&
policy->max >= policy->cpuinfo.max_freq) {
- limits.min_policy_pct = 100;
- limits.min_perf_pct = 100;
- limits.min_perf = int_tofp(1);
- limits.max_policy_pct = 100;
- limits.max_perf_pct = 100;
- limits.max_perf = int_tofp(1);
- limits.no_turbo = 0;
- limits.max_perf_ctl = 0;
- limits.min_perf_ctl = 0;
+ pr_debug("intel_pstate: set performance\n");
+ limits = &performance_limits;
return 0;
}

- limits.min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
- limits.min_policy_pct = clamp_t(int, limits.min_policy_pct, 0 , 100);
- limits.max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
- limits.max_policy_pct = clamp_t(int, limits.max_policy_pct, 0 , 100);
+ pr_debug("intel_pstate: set powersave\n");
+ limits = &powersave_limits;
+ limits->min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
+ limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, 0 , 100);
+ limits->max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
+ limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100);

/* Normalize user input to [min_policy_pct, max_policy_pct] */
- limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
- limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
- limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
- limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
+ limits->min_perf_pct = max(limits->min_policy_pct,
+ limits->min_sysfs_pct);
+ limits->min_perf_pct = min(limits->max_policy_pct,
+ limits->min_perf_pct);
+ limits->max_perf_pct = min(limits->max_policy_pct,
+ limits->max_sysfs_pct);
+ limits->max_perf_pct = max(limits->min_policy_pct,
+ limits->max_perf_pct);

/* Make sure min_perf_pct <= max_perf_pct */
- limits.min_perf_pct = min(limits.max_perf_pct, limits.min_perf_pct);
+ limits->min_perf_pct = min(limits->max_perf_pct, limits->min_perf_pct);

- limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
- limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
+ limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
+ int_tofp(100));
+ limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
+ int_tofp(100));

#if IS_ENABLED(CONFIG_ACPI)
cpu = all_cpu_data[policy->cpu];
@@ -1246,14 +1274,14 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)

control = convert_to_native_pstate_format(cpu, i);
if (control * cpu->pstate.scaling == policy->max)
- limits.max_perf_ctl = control;
+ limits->max_perf_ctl = control;
if (control * cpu->pstate.scaling == policy->min)
- limits.min_perf_ctl = control;
+ limits->min_perf_ctl = control;
}

pr_debug("intel_pstate: max %u policy_max %u perf_ctl [0x%x-0x%x]\n",
- policy->cpuinfo.max_freq, policy->max, limits.min_perf_ctl,
- limits.max_perf_ctl);
+ policy->cpuinfo.max_freq, policy->max, limits->min_perf_ctl,
+ limits->max_perf_ctl);
#endif

if (hwp_active)
@@ -1298,7 +1326,7 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)

cpu = all_cpu_data[policy->cpu];

- if (limits.min_perf_pct == 100 && limits.max_perf_pct == 100)
+ if (limits->min_perf_pct == 100 && limits->max_perf_pct == 100)
policy->policy = CPUFREQ_POLICY_PERFORMANCE;
else
policy->policy = CPUFREQ_POLICY_POWERSAVE;
--
1.8.3.1

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