[PATCH v7 6/6] cpufreq: powernv: Add sysfs attributes to show throttle stats

Shilpasri G Bhat
2016-01-28T07:27:32Z

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

1)/sys/devices/system/cpu/cpufreq/chip0/throttle_frequencies
This gives the throttle stats for each of the available frequencies.
The throttle stat of a frequency is the total number of times the max
frequency is reduced to that frequency.
# cat /sys/devices/system/cpu/cpufreq/chip0/throttle_frequencies
4023000 0
3990000 0
3956000 1
3923000 0
3890000 0
3857000 2
3823000 0
3790000 0
3757000 2
3724000 1
3690000 1
...

2)/sys/devices/system/cpu/cpufreq/chip0/throttle_reasons
This directory contains throttle reason files. Each file gives the
total number of times the max frequency is throttled, except for
'unthrottle_count', which gives the total number of times the max
frequency is unthrottled after being throttled.
# cd /sys/devices/system/cpu/cpufreq/chip0/throttle_reasons
# cat cpu_over_temperature
7
# cat occ_reset
0
# cat over_current
0
# cat power_cap
0
# cat power_supply_failure
0
# cat unthrottle_count
7

3)/sys/devices/system/cpu/cpufreq/chip0/throttle_stat
This gives the total number of events of max frequency throttling to
lower frequencies in the turbo range of frequencies and the sub-turbo(at
and below nominal) range of frequencies.
# cat /sys/devices/system/cpu/cpufreq/chip0/throttle_stat
turbo 7
sub-turbo 0

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Cc: linux-api@vger.kernel.org
---
Changes from v6:
- Rename struct chip members 'throt_{nominal/turbo}' to throttle_*
- Rename sysfs throttle_reason attribute 'throttle_reset' to
'unthrottle_count'
- Add sysfs attribute details in
Documentation/ABI/testing/sysfs-devices-system-cpu
- Add helper routine get_chip_index_from_kobj() for throttle sysfs
attribute show() to get chip index from kobject.
- Add the chip id in the pr_warn_once

No changes from v5.

Changes from v4:
- Taken care of Gautham's comments to use inline get_chip_index()

Changes from v3:
- Seperate the patch to contain only the throttle sysfs attribute changes.
- Add helper inline function get_chip_index()

Changes from v2:
- Fixed kbuild test warning.
drivers/cpufreq/powernv-cpufreq.c:609:2: warning: ignoring return
value of 'kstrtoint', declared with attribute warn_unused_result
[-Wunused-result]

Changes from v1:
- Added a kobject to struct chip
- Grouped the throttle reasons under a separate attribute_group and
exported each reason as individual file.
- Moved the sysfs files from /sys/devices/system/node/nodeN to
/sys/devices/system/cpu/cpufreq/chipN
- As suggested by Paul Clarke replaced 'Nominal' with 'sub-turbo'.

Documentation/ABI/testing/sysfs-devices-system-cpu | 45 +++++
drivers/cpufreq/powernv-cpufreq.c | 205 ++++++++++++++++++++-
2 files changed, 241 insertions(+), 9 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index b683e8e..dea4620 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -271,3 +271,48 @@ 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/cpufreq/chip*/throttle_stats
+Date: Jan 2016
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+ Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: CPU Frequency throttle stat for the chip
+
+ This attribute gives the total number of events of max-frequency
+ throttling to any lower frequency in the turbo(above nominal) and
+ the sub-turbo (at and below nominal) range of frequencies.
+
+
+What: /sys/devices/system/cpu/cpufreq/chip*/throttle_frequencies
+Date: Jan 2016
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+ Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: CPU Frequency throttle stat for all available frequencies in the chip
+
+ This attribute gives the throttle stats for each of the available
+ frequencies. The throttle stat of a frequency is the total
+ number of times the max frequency is reduced to that frequency.
+
+What: /sys/devices/system/cpu/cpufreq/chip*/throttle_reasons/<reason_attributes>
+Date: Jan 2016
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+ Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: CPU Frequency throttle reason stat for the chip
+
+ This directory contains throttle reason files. Each file gives
+ the total number of times the max frequency is throttled, except
+ for 'unthrottle_count', which gives the total number of times
+ the max frequency is unthrottled after being throttled. Below
+ are the reason attributes.
+
+ cpu_over_temperature: Throttled due to cpu over temperature
+
+ occ_reset: Throttled due to reset of OCC
+
+ over_current: Throttled due to over current
+
+ power_cap: Throttled due to power capping
+
+ power_supply_failure: Throttled due to power supply failure
+
+ unthrottle_count: Unthrottled from any of the above reasons.
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 1bbc10a..b647941 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 +72,11 @@ static struct chip {
u8 throttle_reason;
cpumask_t mask;
struct work_struct throttle;
+ int throttle_turbo;
+ int throttle_nominal;
+ int reason[OCC_MAX_REASON];
+ int *pstate_stat;
+ struct kobject *kobj;
} *chips;

static int nr_chips;
@@ -196,6 +211,126 @@ 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;
+}
+
+static inline int get_chip_index_from_kobj(struct kobject *kobj)
+{
+ int ret, id;
+ int len = strlen("chip");
+
+ ret = kstrtoint(kobj->name + len, 0, &id);
+ if (ret)
+ return ret;
+
+ ret = get_chip_index(id);
+ if (ret < 0)
+ pr_warn_once("%s Matching chip-id not found %d\n", __func__,
+ id);
+ return ret;
+}
+
+static ssize_t throttle_freq_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ int i, count = 0, id;
+
+ id = get_chip_index_from_kobj(kobj);
+ if (id < 0)
+ return id;
+
+ for (i = 0; i < powernv_pstate_info.nr_pstates; i++)
+ count += sprintf(&buf[count], "%d %d\n",
+ powernv_freqs[i].frequency,
+ chips[id].pstate_stat[i]);
+
+ return count;
+}
+
+static struct kobj_attribute attr_throttle_frequencies =
+__ATTR(throttle_frequencies, 0444, throttle_freq_show, NULL);
+
+static ssize_t throttle_stat_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ int id, count = 0;
+
+ id = get_chip_index_from_kobj(kobj);
+ if (id < 0)
+ return id;
+
+ count += sprintf(&buf[count], "turbo %d\n", chips[id].throttle_turbo);
+ count += sprintf(&buf[count], "sub-turbo %d\n",
+ chips[id].throttle_nominal);
+
+ return count;
+}
+
+static struct kobj_attribute attr_throttle_stat =
+__ATTR(throttle_stat, 0444, throttle_stat_show, NULL);
+
+#define define_throttle_reason_attr(attr_name, val) \
+static ssize_t attr_name##_show(struct kobject *kobj, \
+ struct kobj_attribute *attr, char *buf) \
+{ \
+ int id; \
+ \
+ id = get_chip_index_from_kobj(kobj); \
+ if (id < 0) \
+ return id; \
+ \
+ return sprintf(buf, "%d\n", chips[id].reason[val]); \
+} \
+ \
+static struct kobj_attribute attr_##attr_name = \
+__ATTR(attr_name, 0444, attr_name##_show, NULL)
+
+define_throttle_reason_attr(unthrottle_count, NO_THROTTLE);
+define_throttle_reason_attr(power_cap, POWERCAP);
+define_throttle_reason_attr(cpu_over_temperature, CPU_OVERTEMP);
+define_throttle_reason_attr(power_supply_failure, POWER_SUPPLY_FAILURE);
+define_throttle_reason_attr(over_current, OVERCURRENT);
+define_throttle_reason_attr(occ_reset, OCC_RESET_THROTTLE);
+
+static struct attribute *throttle_reason_attrs[] = {
+ &attr_unthrottle_count.attr,
+ &attr_power_cap.attr,
+ &attr_cpu_over_temperature.attr,
+ &attr_power_supply_failure.attr,
+ &attr_over_current.attr,
+ &attr_occ_reset.attr,
+ NULL
+};
+
+static struct attribute *throttle_stat_attrs[] = {
+ &attr_throttle_frequencies.attr,
+ &attr_throttle_stat.attr,
+ NULL
+};
+
+static const struct attribute_group throttle_reason_group = {
+ .name = "throttle_reasons",
+ .attrs = throttle_reason_attrs,
+};
+
+static const struct attribute_group throttle_stat_group = {
+ .attrs = throttle_stat_attrs,
+};
+
+static const struct attribute_group *throttle_attr_groups[] = {
+ &throttle_stat_group,
+ &throttle_reason_group,
+ NULL
+};
+
/* Helper routines */

/* Access helpers to power mgt SPR */
@@ -327,13 +462,16 @@ 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 long pmsr;
- int pmsr_pmax, i;
+ int pmsr_pmax, i, index;

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 +479,19 @@ 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++;
+ }
+
+ index = powernv_pstate_info.max - pmsr_pmax;
+ if (index >= 0 && index < powernv_pstate_info.nr_pstates)
+ chips[i].pstate_stat[index]++;
+
trace_powernv_throttle(chips[i].id,
throttle_reason[chips[i].throttle_reason],
pmsr_pmax);
@@ -512,13 +659,19 @@ 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;
@@ -583,12 +736,38 @@ static int init_chip_info(void)
goto free_chip_map;

for (i = 0; i < nr_chips; i++) {
+ char name[10];
+
chips[i].id = chip[i];
cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
+ chips[i].pstate_stat = kcalloc(powernv_pstate_info.nr_pstates,
+ sizeof(int), GFP_KERNEL);
+ if (!chips[i].pstate_stat)
+ goto free;
+
+ sprintf(name, "chip%d", chips[i].id);
+ chips[i].kobj = kobject_create_and_add(name,
+ cpufreq_global_kobject);
+ if (!chips[i].kobj)
+ goto free;
+
+ ret = sysfs_create_groups(chips[i].kobj, throttle_attr_groups);
+ if (ret) {
+ pr_info("Chip %d failed to create throttle sysfs group\n",
+ chips[i].id);
+ goto free;
+ }
}

return 0;
+free:
+ nr_chips = i;
+ for (i = 0; i <= nr_chips; i++) {
+ kobject_put(chips[i].kobj);
+ kfree(chips[i].pstate_stat);
+ }
+ kfree(chips);
free_chip_map:
kfree(core_to_chip_map);
out:
@@ -623,9 +802,17 @@ module_init(powernv_cpufreq_init);

static void __exit powernv_cpufreq_exit(void)
{
+ int i;
+
unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
opal_message_notifier_unregister(OPAL_MSG_OCC,
&powernv_cpufreq_opal_nb);
+
+ for (i = 0; i < nr_chips; i++) {
+ kobject_put(chips[i].kobj);
+ kfree(chips[i].pstate_stat);
+ }
+
kfree(chips);
kfree(core_to_chip_map);
cpufreq_unregister_driver(&powernv_cpufreq_driver);
--
1.9.3