[PATCH v9] cpufreq: powernv: Add sysfs attributes to show throttle stats

Shilpasri G Bhat
2016-02-08T14:45:32Z

Create sysfs attributes to export throttle information in
/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats directory. The
newly added sysfs files are as follows:

1)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat
2)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub-turbo_stat
3)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle
4)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap
5)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp
6)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault
7)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent
8)/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset

Detailed explanation of each attribute is added to
Documentation/ABI/testing/sysfs-devices-system-cpu

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
---
Changes from v8:
- Moved the sysfs attributes from cpu/cpufreq/chipX to cpuX/cpufreq/throttle_stats
- Adhering to one-value-per-file, replace throttle_table with multiple
sysfs files.
- Using CPUFREQ_POLICY_NOTIFIER to add/remove attribute_group.

Documentation/ABI/testing/sysfs-devices-system-cpu | 46 ++++++++
drivers/cpufreq/powernv-cpufreq.c | 128 +++++++++++++++++++--
2 files changed, 165 insertions(+), 9 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index b683e8e..2d52ef5 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -271,3 +271,49 @@ Description: Parameters for the CPU cache attributes
- WriteBack: data is written only to the cache line and
the modified cache line is written to main
memory only when it is replaced
+
+What: /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub_turbo_stat
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent
+ /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset
+Date: Feb 2016
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+ Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: POWERNV CPUFreq driver's frequency throttle stats directory and
+ attributes
+
+ 'cpuX/cpufreq/throttle_stats' directory contains the CPU
+ frequency throttle stat attributes. The throttle stats are common
+ for the chip. Below are the throttle attributes exported in the
+ 'throttle_stats' directory:
+
+ - turbo_stat : This file gives the total number of times the max
+ frequency is throttled to lower frequency in turbo (at and above
+ nominal frequency) range of frequencues.
+
+ - sub_turbo_stat : This file gives the total number of times the
+ max frequency is throttled to lower frequency in sub-turbo(below
+ nominal frequency) range of frequencies.
+
+ - unthrottle : This file gives the total number of times the max
+ frequency is unthrottled after being throttled.
+
+ - powercap : This file gives the total number of times the max
+ frequency is throttled due to 'Power Capping'.
+
+ - overtemp : This file gives the total number of times the max
+ frequency is throttled due to 'CPU Over Temperature'.
+
+ - supply_fault : This file gives the total number of times the
+ max frequency is throttled due to 'Power Supply Failure'.
+
+ - overcurrent : This file gives the total number of times the
+ max frequency is throttled due to 'Overcurrent'.
+
+ - occ_reset : This file gives the total number of times the max
+ frequency is throttled due to 'OCC Reset'.
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 1bbc10a..94f225f 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -55,6 +55,16 @@ static const char * const throttle_reason[] = {
"OCC Reset"
};

+enum throttle_reason_type {
+ NO_THROTTLE = 0,
+ POWERCAP,
+ CPU_OVERTEMP,
+ POWER_SUPPLY_FAILURE,
+ OVERCURRENT,
+ OCC_RESET_THROTTLE,
+ OCC_MAX_REASON
+};
+
static struct chip {
unsigned int id;
bool throttled;
@@ -62,6 +72,9 @@ static struct chip {
u8 throttle_reason;
cpumask_t mask;
struct work_struct throttle;
+ int throttle_turbo;
+ int throttle_nominal;
+ int reason[OCC_MAX_REASON];
} *chips;

static int nr_chips;
@@ -196,6 +209,62 @@ static struct freq_attr *powernv_cpu_freq_attr[] = {
NULL,
};

+static inline int get_chip_index(unsigned int id)
+{
+ int i;
+
+ for (i = 0; i < nr_chips; i++)
+ if (chips[i].id == id)
+ return i;
+
+ return -EINVAL;
+}
+
+#define get_chip_id(cpu) core_to_chip_map[cpu_core_index_of_thread(cpu)]
+
+#define throttle_attr(name, member) \
+static ssize_t name##_show(struct cpufreq_policy *policy, char *buf) \
+{ \
+ int id; \
+ \
+ id = get_chip_index(get_chip_id(policy->cpu)); \
+ if (id < 0) { \
+ pr_warn_once("%s Matching chip-id not found %d\n", \
+ __func__, get_chip_id(policy->cpu)); \
+ return id; \
+ } \
+ \
+ return sprintf(buf, "%u\n", chips[id].member); \
+} \
+ \
+static struct freq_attr throttle_attr_##name = __ATTR_RO(name) \
+
+throttle_attr(unthrottle, reason[NO_THROTTLE]);
+throttle_attr(powercap, reason[POWERCAP]);
+throttle_attr(overtemp, reason[CPU_OVERTEMP]);
+throttle_attr(supply_fault, reason[POWER_SUPPLY_FAILURE]);
+throttle_attr(overcurrent, reason[OVERCURRENT]);
+throttle_attr(occ_reset, reason[OCC_RESET_THROTTLE]);
+throttle_attr(turbo_stat, throttle_turbo);
+throttle_attr(sub_turbo_stat, throttle_nominal);
+
+static struct attribute *throttle_attrs[] = {
+ &throttle_attr_unthrottle.attr,
+ &throttle_attr_powercap.attr,
+ &throttle_attr_overtemp.attr,
+ &throttle_attr_supply_fault.attr,
+ &throttle_attr_overcurrent.attr,
+ &throttle_attr_occ_reset.attr,
+ &throttle_attr_turbo_stat.attr,
+ &throttle_attr_sub_turbo_stat.attr,
+ NULL,
+};
+
+static const struct attribute_group throttle_attr_grp = {
+ .name = "throttle_stats",
+ .attrs = throttle_attrs,
+};
+
/* Helper routines */

/* Access helpers to power mgt SPR */
@@ -325,15 +394,18 @@ static inline unsigned int get_nominal_index(void)
static void powernv_cpufreq_throttle_check(void *data)
{
unsigned int cpu = smp_processor_id();
- unsigned int chip_id = core_to_chip_map[cpu_core_index_of_thread(cpu)];
+ unsigned int chip_id = get_chip_id(cpu);
unsigned long pmsr;
int pmsr_pmax, i;

pmsr = get_pmspr(SPRN_PMSR);

- for (i = 0; i < nr_chips; i++)
- if (chips[i].id == chip_id)
- break;
+ i = get_chip_index(chip_id);
+ if (unlikely(i < 0)) {
+ pr_warn_once("%s Matching chip-id not found %d\n", __func__,
+ chip_id);
+ return;
+ }

/* Check for Pmax Capping */
pmsr_pmax = (s8)PMSR_MAX(pmsr);
@@ -341,10 +413,15 @@ static void powernv_cpufreq_throttle_check(void *data)
if (chips[i].throttled)
goto next;
chips[i].throttled = true;
- if (pmsr_pmax < powernv_pstate_info.nominal)
+ if (pmsr_pmax < powernv_pstate_info.nominal) {
pr_warn_once("CPU %d on Chip %u has Pmax reduced below nominal frequency (%d < %d)\n",
cpu, chips[i].id, pmsr_pmax,
powernv_pstate_info.nominal);
+ chips[i].throttle_nominal++;
+ } else {
+ chips[i].throttle_turbo++;
+ }
+
trace_powernv_throttle(chips[i].id,
throttle_reason[chips[i].throttle_reason],
pmsr_pmax);
@@ -512,13 +589,18 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
return 0;
}

- for (i = 0; i < nr_chips; i++)
- if (chips[i].id == omsg.chip)
- break;
+ i = get_chip_index(omsg.chip);
+ if (i < 0) {
+ pr_warn_once("%s Matching chip-id not found %d\n",
+ __func__, (int)omsg.chip);
+ return i;
+ }

if (omsg.throttle_status >= 0 &&
- omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS)
+ omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS) {
chips[i].throttle_reason = omsg.throttle_status;
+ chips[i].reason[omsg.throttle_status]++;
+ }

if (!omsg.throttle_status)
chips[i].restore = true;
@@ -534,6 +616,29 @@ static struct notifier_block powernv_cpufreq_opal_nb = {
.priority = 0,
};

+static int powernv_cpufreq_policy_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct cpufreq_policy *policy = data;
+ int ret;
+
+ if (action == CPUFREQ_CREATE_POLICY) {
+ ret = sysfs_create_group(&policy->kobj, &throttle_attr_grp);
+ if (ret)
+ pr_info("Failed to create throttle stats directory for cpu %d\n",
+ policy->cpu);
+ } else if (action == CPUFREQ_REMOVE_POLICY) {
+ sysfs_remove_group(&policy->kobj, &throttle_attr_grp);
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block powernv_cpufreq_policy_nb = {
+ .notifier_call = powernv_cpufreq_policy_notifier,
+ .next = NULL,
+};
+
static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
{
struct powernv_smp_call_data freq_data;
@@ -589,6 +694,7 @@ static int init_chip_info(void)
}

return 0;
+
free_chip_map:
kfree(core_to_chip_map);
out:
@@ -615,6 +721,8 @@ static int __init powernv_cpufreq_init(void)
if (rc)
return rc;

+ cpufreq_register_notifier(&powernv_cpufreq_policy_nb,
+ CPUFREQ_POLICY_NOTIFIER);
register_reboot_notifier(&powernv_cpufreq_reboot_nb);
opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
return cpufreq_register_driver(&powernv_cpufreq_driver);
@@ -626,6 +734,8 @@ static void __exit powernv_cpufreq_exit(void)
unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
opal_message_notifier_unregister(OPAL_MSG_OCC,
&powernv_cpufreq_opal_nb);
+ cpufreq_unregister_notifier(&powernv_cpufreq_policy_nb,
+ CPUFREQ_POLICY_NOTIFIER);
kfree(chips);
kfree(core_to_chip_map);
cpufreq_unregister_driver(&powernv_cpufreq_driver);
--
1.9.3