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cpufreq: intel_pstate: Fix intel_pstate powersave min_perf_pct value
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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 a047599
("[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.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Prarit Bhargava authored and Rafael J. Wysocki committed Oct 16, 2015
1 parent 7855e10 commit 51443fb
Showing 1 changed file with 85 additions and 57 deletions.
142 changes: 85 additions & 57 deletions drivers/cpufreq/intel_pstate.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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);
}
Expand All @@ -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;
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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;
}
Expand All @@ -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();
Expand All @@ -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();
Expand All @@ -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();
Expand Down Expand Up @@ -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(
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -905,29 +932,29 @@ 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;

/*
* performance can be limited by user through sysfs, by cpufreq
* 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);
}
}
Expand Down Expand Up @@ -1215,34 +1242,35 @@ 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];
Expand All @@ -1251,14 +1279,14 @@ 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)
Expand Down Expand Up @@ -1303,7 +1331,7 @@ 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;
Expand Down

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