[PATCH v5 0/5] cpufreq: powernv: Redesign the presentation of throttle notification and solve bug-fixes in the driver

[PATCH v5 0/5] cpufreq: powernv: Redesign the presentation of throttle notification and solve bug-fixes in the driver

[Shilpasri G Bhat]

In POWER8, OCC(On-Chip-Controller) can throttle the frequency of the
CPU when the chip crosses its thermal and power limits. Currently,
powernv-cpufreq driver detects and reports this event as a console
message. Some machines may not sustain the max turbo frequency in all
conditions and can be throttled frequently. This can lead to the
flooding of console with throttle messages. So this patchset aims to
redesign the presentation of this event via sysfs counters and
tracepoints. And it also fixes couple of bugs reported in the driver.

- Patch [1] fixes the cpu hot-plug bug in powernv_cpufreq_work_fn().
- Patch [2] solves a bug in powernv_cpufreq_throttle_check(), which
  calls in to cpu_to_chip_id() in hot path which reads DT every time
  to find the chip id.
- Patches [3] to [5] will add a perf trace point
  "power:powernv_throttle" and sysfs throttle counter stats in
  /sys/devices/system/cpu/cpufreq/chipN.

Changes from v4:
- Fix a hot-plug bug in powernv_cpufreq_work_fn()
- Changes wrt Gautham's and Shreyas's comments 

Changes from v3:
- Add a fix to replace cpu_to_chip_id() with simpler PIR shift to 
  obtain the chip id.
- Break patch2 in to two patches separating the tracepoint and sysfs
  attribute changes.

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]

Shilpasri G Bhat (5):
  cpufreq: powernv: Hot-plug safe the kworker thread
  cpufreq: powernv: Remove cpu_to_chip_id() from hot-path
  cpufreq: powernv/tracing: Add powernv_throttle tracepoint
  cpufreq: powernv: Replace pr_info with trace print for throttle event
  cpufreq: powernv: Add sysfs attributes to show throttle stats

 drivers/cpufreq/powernv-cpufreq.c | 312 +++++++++++++++++++++++++++++++-------
 include/trace/events/power.h      |  22 +++
 kernel/trace/power-traces.c       |   1 +
 3 files changed, 280 insertions(+), 55 deletions(-)

-- 
1.9.3

[PATCH v5 1/5] cpufreq: powernv: Hot-plug safe the kworker thread

[Shilpasri G Bhat]

In the kworker_thread powernv_cpufreq_work_fn(), we can end up
sending an IPI to a cpu going offline. This is a rare corner case
which is fixed using {get/put}_online_cpus(). Along with this fix,
this patch adds changes to do oneshot cpumask_{clear/and} operation.

Suggested-by: Shreyas B Prabhu <shreyas@linux.vnet.ibm.com>
Suggested-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
 drivers/cpufreq/powernv-cpufreq.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 547890f..50a5b21 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -423,18 +423,19 @@ void powernv_cpufreq_work_fn(struct work_struct *work)
 {
 	struct chip *chip = container_of(work, struct chip, throttle);
 	unsigned int cpu;
-	cpumask_var_t mask;
+	cpumask_t mask;
 
-	smp_call_function_any(&chip->mask,
+	get_online_cpus();
+	cpumask_and(&mask, &chip->mask, cpu_online_mask);
+	smp_call_function_any(&mask,
 			      powernv_cpufreq_throttle_check, NULL, 0);
 
 	if (!chip->restore)
-		return;
+		goto out;
 
 	chip->restore = false;
-	cpumask_copy(mask, &chip->mask);
-	for_each_cpu_and(cpu, mask, cpu_online_mask) {
-		int index, tcpu;
+	for_each_cpu(cpu, &mask) {
+		int index;
 		struct cpufreq_policy policy;
 
 		cpufreq_get_policy(&policy, cpu);
@@ -442,9 +443,10 @@ void powernv_cpufreq_work_fn(struct work_struct *work)
 					       policy.cur,
 					       CPUFREQ_RELATION_C, &index);
 		powernv_cpufreq_target_index(&policy, index);
-		for_each_cpu(tcpu, policy.cpus)
-			cpumask_clear_cpu(tcpu, mask);
+		cpumask_andnot(&mask, &mask, policy.cpus);
 	}
+out:
+	put_online_cpus();
 }
 
 static char throttle_reason[][30] = {
-- 
1.9.3

[PATCH v5 2/5] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path

[Shilpasri G Bhat]

cpu_to_chip_id() does a DT walk through to find out the chip id by
taking a contended device tree lock. This adds an unnecessary overhead
in a hot path. So instead of calling cpu_to_chip_id() everytime cache
the chip ids for all cores in the array 'core_to_chip_map' and use it
in the hotpath.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
Changes from v4:
- Taken care of Shreyas's comments to add a core_to_chip_map array to
  store the chip id.

 drivers/cpufreq/powernv-cpufreq.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 50a5b21..5ea103d 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -42,6 +42,7 @@
 
 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
 static bool rebooting, throttled, occ_reset;
+static unsigned int *core_to_chip_map;
 
 static struct chip {
 	unsigned int id;
@@ -312,13 +313,14 @@ 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 long pmsr;
 	int pmsr_pmax, i;
 
 	pmsr = get_pmspr(SPRN_PMSR);
 
 	for (i = 0; i < nr_chips; i++)
-		if (chips[i].id == cpu_to_chip_id(cpu))
+		if (chips[i].id == chip_id)
 			break;
 
 	/* Check for Pmax Capping */
@@ -558,19 +560,29 @@ static int init_chip_info(void)
 	unsigned int chip[256];
 	unsigned int cpu, i;
 	unsigned int prev_chip_id = UINT_MAX;
+	cpumask_t cpu_mask;
+	int ret = -ENOMEM;
 
-	for_each_possible_cpu(cpu) {
+	cpumask_copy(&cpu_mask, cpu_possible_mask);
+	core_to_chip_map = kcalloc(cpu_nr_cores(), sizeof(unsigned int),
+				   GFP_KERNEL);
+	if (!core_to_chip_map)
+		goto out;
+
+	for_each_cpu(cpu, &cpu_mask) {
 		unsigned int id = cpu_to_chip_id(cpu);
 
 		if (prev_chip_id != id) {
 			prev_chip_id = id;
 			chip[nr_chips++] = id;
 		}
+		core_to_chip_map[cpu_core_index_of_thread(cpu)] = id;
+		cpumask_andnot(&cpu_mask, &cpu_mask, cpu_sibling_mask(cpu));
 	}
 
 	chips = kmalloc_array(nr_chips, sizeof(struct chip), GFP_KERNEL);
 	if (!chips)
-		return -ENOMEM;
+		goto free_chip_map;
 
 	for (i = 0; i < nr_chips; i++) {
 		chips[i].id = chip[i];
@@ -581,6 +593,10 @@ static int init_chip_info(void)
 	}
 
 	return 0;
+free_chip_map:
+	kfree(core_to_chip_map);
+out:
+	return ret;
 }
 
 static int __init powernv_cpufreq_init(void)
@@ -614,6 +630,8 @@ 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);
+	kfree(chips);
+	kfree(core_to_chip_map);
 	cpufreq_unregister_driver(&powernv_cpufreq_driver);
 }
 module_exit(powernv_cpufreq_exit);
-- 
1.9.3

[PATCH v5 3/5] cpufreq: powernv/tracing: Add powernv_throttle tracepoint

[Shilpasri G Bhat]

This patch adds the powernv_throttle tracepoint to trace the CPU
frequency throttling event, which is used by the powernv-cpufreq
driver in POWER8.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: Steven Rostedt <rostedt@goodmis.org>
---
No changes since v2.

 include/trace/events/power.h | 22 ++++++++++++++++++++++
 kernel/trace/power-traces.c  |  1 +
 2 files changed, 23 insertions(+)

diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index 284244e..19e5030 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -38,6 +38,28 @@ DEFINE_EVENT(cpu, cpu_idle,
 	TP_ARGS(state, cpu_id)
 );
 
+TRACE_EVENT(powernv_throttle,
+
+	TP_PROTO(int chip_id, const char *reason, int pmax),
+
+	TP_ARGS(chip_id, reason, pmax),
+
+	TP_STRUCT__entry(
+		__field(int, chip_id)
+		__string(reason, reason)
+		__field(int, pmax)
+	),
+
+	TP_fast_assign(
+		__entry->chip_id = chip_id;
+		__assign_str(reason, reason);
+		__entry->pmax = pmax;
+	),
+
+	TP_printk("Chip %d Pmax %d %s", __entry->chip_id,
+		  __entry->pmax, __get_str(reason))
+);
+
 TRACE_EVENT(pstate_sample,
 
 	TP_PROTO(u32 core_busy,
diff --git a/kernel/trace/power-traces.c b/kernel/trace/power-traces.c
index eb4220a..81b8745 100644
--- a/kernel/trace/power-traces.c
+++ b/kernel/trace/power-traces.c
@@ -15,4 +15,5 @@
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(suspend_resume);
 EXPORT_TRACEPOINT_SYMBOL_GPL(cpu_idle);
+EXPORT_TRACEPOINT_SYMBOL_GPL(powernv_throttle);
 
-- 
1.9.3

[PATCH v5 4/5] cpufreq: powernv: Replace pr_info with trace print for throttle event

[Shilpasri G Bhat]

Currently we use printk message to notify the throttle event. But this
can flood the console if the cpu is throttled frequently. So replace the
printk with the tracepoint to notify the throttle event. And also events
like throttle below nominal frequency and OCC_RESET are reduced to
pr_warn/pr_warn_once as pointed by MFG to not mark them as critical
messages. This patch adds 'throt_reason' to struct chip to store the
throttle reason.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
Changes from v4:
- Taken care of Gautham's comments to remove the new function
  powernv_cpufreq_check_pmax()
- Modified commit message

Changes from v3:
- Separate this patch to contain trace_point changes
- Move struct chip member 'restore' of type bool above 'mask' to reduce
  structure padding.

No changes from v2.

Changes from v1:
- As suggested by Paul Clarke replaced char * throttle_reason[][30] by 
  const char * const throttle_reason[].

 drivers/cpufreq/powernv-cpufreq.c | 73 ++++++++++++++++++---------------------
 1 file changed, 34 insertions(+), 39 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 5ea103d..0ed7d82 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -28,6 +28,7 @@
 #include <linux/of.h>
 #include <linux/reboot.h>
 #include <linux/slab.h>
+#include <trace/events/power.h>
 
 #include <asm/cputhreads.h>
 #include <asm/firmware.h>
@@ -44,12 +45,22 @@ static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
 static bool rebooting, throttled, occ_reset;
 static unsigned int *core_to_chip_map;
 
+static const char * const throttle_reason[] = {
+	"No throttling",
+	"Power Cap",
+	"Processor Over Temperature",
+	"Power Supply Failure",
+	"Over Current",
+	"OCC Reset"
+};
+
 static struct chip {
 	unsigned int id;
 	bool throttled;
+	bool restore;
+	u8 throt_reason;
 	cpumask_t mask;
 	struct work_struct throttle;
-	bool restore;
 } *chips;
 
 static int nr_chips;
@@ -330,17 +341,17 @@ static void powernv_cpufreq_throttle_check(void *data)
 			goto next;
 		chips[i].throttled = true;
 		if (pmsr_pmax < powernv_pstate_info.nominal)
-			pr_crit("CPU %d on Chip %u has Pmax reduced below nominal frequency (%d < %d)\n",
-				cpu, chips[i].id, pmsr_pmax,
-				powernv_pstate_info.nominal);
-		else
-			pr_info("CPU %d on Chip %u has Pmax reduced below turbo frequency (%d < %d)\n",
-				cpu, chips[i].id, pmsr_pmax,
-				powernv_pstate_info.max);
+			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);
+		trace_powernv_throttle(chips[i].id,
+				       throttle_reason[chips[i].throt_reason],
+				       pmsr_pmax);
 	} else if (chips[i].throttled) {
 		chips[i].throttled = false;
-		pr_info("CPU %d on Chip %u has Pmax restored to %d\n", cpu,
-			chips[i].id, pmsr_pmax);
+		trace_powernv_throttle(chips[i].id,
+				       throttle_reason[chips[i].throt_reason],
+				       pmsr_pmax);
 	}
 
 	/* Check if Psafe_mode_active is set in PMSR. */
@@ -358,7 +369,7 @@ next:
 
 	if (throttled) {
 		pr_info("PMSR = %16lx\n", pmsr);
-		pr_crit("CPU Frequency could be throttled\n");
+		pr_warn("CPU Frequency could be throttled\n");
 	}
 }
 
@@ -451,15 +462,6 @@ out:
 	put_online_cpus();
 }
 
-static char throttle_reason[][30] = {
-					"No throttling",
-					"Power Cap",
-					"Processor Over Temperature",
-					"Power Supply Failure",
-					"Over Current",
-					"OCC Reset"
-				     };
-
 static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 				   unsigned long msg_type, void *_msg)
 {
@@ -485,7 +487,7 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 		 */
 		if (!throttled) {
 			throttled = true;
-			pr_crit("CPU frequency is throttled for duration\n");
+			pr_warn("CPU frequency is throttled for duration\n");
 		}
 
 		break;
@@ -509,23 +511,18 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 			return 0;
 		}
 
-		if (omsg.throttle_status &&
+		for (i = 0; i < nr_chips; i++)
+			if (chips[i].id == omsg.chip)
+				break;
+
+		if (omsg.throttle_status >= 0 &&
 		    omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS)
-			pr_info("OCC: Chip %u Pmax reduced due to %s\n",
-				(unsigned int)omsg.chip,
-				throttle_reason[omsg.throttle_status]);
-		else if (!omsg.throttle_status)
-			pr_info("OCC: Chip %u %s\n", (unsigned int)omsg.chip,
-				throttle_reason[omsg.throttle_status]);
-		else
-			return 0;
+			chips[i].throt_reason = omsg.throttle_status;
 
-		for (i = 0; i < nr_chips; i++)
-			if (chips[i].id == omsg.chip) {
-				if (!omsg.throttle_status)
-					chips[i].restore = true;
-				schedule_work(&chips[i].throttle);
-			}
+		if (!omsg.throttle_status)
+			chips[i].restore = true;
+
+		schedule_work(&chips[i].throttle);
 	}
 	return 0;
 }
@@ -580,16 +577,14 @@ static int init_chip_info(void)
 		cpumask_andnot(&cpu_mask, &cpu_mask, cpu_sibling_mask(cpu));
 	}
 
-	chips = kmalloc_array(nr_chips, sizeof(struct chip), GFP_KERNEL);
+	chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
 	if (!chips)
 		goto free_chip_map;
 
 	for (i = 0; i < nr_chips; i++) {
 		chips[i].id = chip[i];
-		chips[i].throttled = false;
 		cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
 		INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
-		chips[i].restore = false;
 	}
 
 	return 0;
-- 
1.9.3

[PATCH v5 5/5] cpufreq: powernv: Add sysfs attributes to show throttle stats

[Shilpasri G Bhat]

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
  'throttle_reset', 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 throttle_reset
  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>
---
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'.
- Modified the commit message.

 drivers/cpufreq/powernv-cpufreq.c | 205 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 196 insertions(+), 9 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 0ed7d82..ecda5f7 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -54,6 +54,16 @@ static const char * const throttle_reason[] = {
 	"OCC Reset"
 };
 
+enum throt_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;
@@ -61,6 +71,11 @@ static struct chip {
 	u8 throt_reason;
 	cpumask_t mask;
 	struct work_struct throttle;
+	int throt_turbo;
+	int throt_nominal;
+	int reason[OCC_MAX_REASON];
+	int *pstate_stat;
+	struct kobject *kobj;
 } *chips;
 
 static int nr_chips;
@@ -195,6 +210,128 @@ 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 ssize_t throttle_freq_show(struct kobject *kobj,
+				  struct kobj_attribute *attr, char *buf)
+{
+	int i, count = 0, id;
+
+	i = kstrtoint(kobj->name + 4, 0, &id);
+	if (i)
+		return i;
+
+	id = get_chip_index(id);
+	if (id < 0) {
+		pr_warn_once("%s Matching chip-id not found\n", __func__);
+		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 ret, id, count = 0;
+
+	ret = kstrtoint(kobj->name + 4, 0, &id);
+	if (ret)
+		return ret;
+
+	id = get_chip_index(id);
+	if (id < 0) {
+		pr_warn_once("%s Matching chip-id not found\n", __func__);
+		return id;
+	}
+
+	count += sprintf(&buf[count], "turbo %d\n", chips[id].throt_turbo);
+	count += sprintf(&buf[count], "sub-turbo %d\n",
+					chips[id].throt_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 ret, id;							  \
+									  \
+	ret = kstrtoint(kobj->name + 4, 0, &id);			  \
+	if (ret)							  \
+		return ret;						  \
+									  \
+	id = get_chip_index(id);					  \
+	if (id < 0) {							  \
+		pr_warn_once("%s Matching chip-id not found\n", __func__);\
+		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(throttle_reset, 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_throttle_reset.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 */
@@ -326,13 +463,15 @@ 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\n", __func__);
+		return;
+	}
 
 	/* Check for Pmax Capping */
 	pmsr_pmax = (s8)PMSR_MAX(pmsr);
@@ -340,10 +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].throt_nominal++;
+		} else {
+			chips[i].throt_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].throt_reason],
 				       pmsr_pmax);
@@ -511,13 +659,18 @@ 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\n",
+				     __func__);
+			return i;
+		}
 
 		if (omsg.throttle_status >= 0 &&
-		    omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS)
+		    omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS) {
 			chips[i].throt_reason = omsg.throttle_status;
+			chips[i].reason[omsg.throttle_status]++;
+		}
 
 		if (!omsg.throttle_status)
 			chips[i].restore = true;
@@ -582,12 +735,38 @@ 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:
@@ -622,9 +801,17 @@ 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

Re: [PATCH v5 1/5] cpufreq: powernv: Hot-plug safe the kworker thread

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 2746 bytes --]

Hi Shilpasri,

[auto build test ERROR on pm/linux-next]
[also build test ERROR on v4.4 next-20160121]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Shilpasri-G-Bhat/cpufreq-powernv-Redesign-the-presentation-of-throttle-notification-and-solve-bug-fixes-in-the-driver/20160121-174402
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: powerpc-allyesconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

Note: the linux-review/Shilpasri-G-Bhat/cpufreq-powernv-Redesign-the-presentation-of-throttle-notification-and-solve-bug-fixes-in-the-driver/20160121-174402 HEAD 9aca97b0876d0d182772832e0447a9bf58a967f7 builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   drivers/cpufreq/powernv-cpufreq.c: In function 'powernv_cpufreq_work_fn':
>> drivers/cpufreq/powernv-cpufreq.c:428:2: error: implicit declaration of function 'get_online_cpus' [-Werror=implicit-function-declaration]
     get_online_cpus();
     ^
>> drivers/cpufreq/powernv-cpufreq.c:449:2: error: implicit declaration of function 'put_online_cpus' [-Werror=implicit-function-declaration]
     put_online_cpus();
     ^
   cc1: some warnings being treated as errors

vim +/get_online_cpus +428 drivers/cpufreq/powernv-cpufreq.c

   422	void powernv_cpufreq_work_fn(struct work_struct *work)
   423	{
   424		struct chip *chip = container_of(work, struct chip, throttle);
   425		unsigned int cpu;
   426		cpumask_t mask;
   427	
 > 428		get_online_cpus();
   429		cpumask_and(&mask, &chip->mask, cpu_online_mask);
   430		smp_call_function_any(&mask,
   431				      powernv_cpufreq_throttle_check, NULL, 0);
   432	
   433		if (!chip->restore)
   434			goto out;
   435	
   436		chip->restore = false;
   437		for_each_cpu(cpu, &mask) {
   438			int index;
   439			struct cpufreq_policy policy;
   440	
   441			cpufreq_get_policy(&policy, cpu);
   442			cpufreq_frequency_table_target(&policy, policy.freq_table,
   443						       policy.cur,
   444						       CPUFREQ_RELATION_C, &index);
   445			powernv_cpufreq_target_index(&policy, index);
   446			cpumask_andnot(&mask, &mask, policy.cpus);
   447		}
   448	out:
 > 449		put_online_cpus();
   450	}
   451	
   452	static char throttle_reason[][30] = {

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 47524 bytes --]

Re: [PATCH v5 5/5] cpufreq: powernv: Add sysfs attributes to show throttle stats

[Gautham R Shenoy]

On Thu, Jan 21, 2016 at 03:08:59PM +0530, Shilpasri G Bhat wrote:
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

--
Thanks and Regards
gautham.