[PATCH v3 3/4] perf,x86: add Intel RAPL PMU support

[Stephane Eranian]

This patch adds a new uncore PMU to expose the Intel
RAPL energy consumption counters. Up to 3 counters,
each counting a particular RAPL event are exposed.

The RAPL counters are available on Intel SandyBridge,
IvyBridge, Haswell. The server skus add a 3rd counter.

The following events are available and exposed in sysfs:
- power/energy-cores: power consumption of all cores on socket
- power/energy-pkg: power consumption of all cores + LLc cache
- power/energy-dram: power consumption of DRAM (servers only)

For each event both the unit (Joules) and scale (0.23 nJ)
is exposed in sysfs for use by perf stat and other tools.
Files are:
	/sys/devices/power/events/energy-*.unit
	/sys/devices/power/events/energy-*.scale

The RAPL PMU is uncore by nature and is implemented such
that it only works in system-wide mode. Measuring only
one CPU per socket is sufficient. The /sys/devices/power/cpumask
file can be used by tools to figure out which CPUs
to monitor by default. For instance, on a 2-socket system, 2 CPUs
(one on each socket) will be shown.

The counters all count in the same unit (exposed via sysfs).
The perf_events API exposes all RAPL counters as 64-bit integers
counting in unit of 1/2^32 Joules (or 0.23 nJ). User level tools
must convert the counts by multiplying them by 0.23 and divide 10^9
to obtain Joules. The reason for this is that the kernel avoids
doing floating point math whenever possible because it is
expensive (user floating-point state must be saved). The method
used avoids kernel floating-point and minimizes the loss of
precision (bits). Thanks to PeterZ for suggesting this approach.

To convert the raw count in Watt:
   W = C * 0.23 / (1e9 * time)
or ldexp(C, -32).

RAPL PMU is a new standalone PMU which registers with the
perf_event core subsystem. The PMU type (attr->type) is
dynamically allocated and is available from /sys/device/power/type.

Sampling is not supported by the RAPL PMU. There is no
privilege level filtering either.

Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
---
 arch/x86/kernel/cpu/Makefile                |    2 +-
 arch/x86/kernel/cpu/perf_event_intel_rapl.c |  652 +++++++++++++++++++++++++++
 2 files changed, 653 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kernel/cpu/perf_event_intel_rapl.c

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 47b56a7..6359506 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -36,7 +36,7 @@ obj-$(CONFIG_CPU_SUP_AMD)		+= perf_event_amd_iommu.o
 endif
 obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_p6.o perf_event_knc.o perf_event_p4.o
 obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_lbr.o perf_event_intel_ds.o perf_event_intel.o
-obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_uncore.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_uncore.o perf_event_intel_rapl.o
 endif
 
 
diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
new file mode 100644
index 0000000..c61b411
--- /dev/null
+++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
@@ -0,0 +1,652 @@
+/*
+ * perf_event_intel_rapl.c: support Intel RAPL energy consumption counters
+ * Copyright (C) 2013 Google, Inc., Stephane Eranian
+ *
+ * Intel RAPL interface is specified in the IA-32 Manual Vol3b
+ * section 14.7.1 (September 2013)
+ *
+ * RAPL provides more controls than just reporting energy consumption
+ * however here we only expose the 3 energy consumption free running
+ * counters (pp0, pkg, dram).
+ *
+ * Each of those counters increments in a power unit defined by the
+ * RAPL_POWER_UNIT MSR. On SandyBridge, this unit is 1/(2^16) Joules
+ * but it can vary.
+ *
+ * Counter to rapl events mappings:
+ *
+ *  pp0 counter: consumption of all physical cores (power plane 0)
+ *	  event: power/energy_cores
+ *    perf code: 0x1
+ *
+ *  pkg counter: consumption of the whole processor package
+ *	  event: power/energy_pkg
+ *    perf code: 0x2
+ *
+ * dram counter: consumption of the dram domain (servers only)
+ *	  event: power/energy_dram
+ *    perf code: 0x3
+ *
+ * We manage those counters as free running (read-only). They may be
+ * use simultaneously by other tools, such as turbostat.
+ *
+ * The events only support system-wide mode counting. There is no
+ * sampling support because it does not make sense and is not
+ * supported by the RAPL hardware.
+ *
+ * Because we want to avoid floating-point operations in the kernel,
+ * the events are all reported in fixed point arithmetic (32.32).
+ * Tools must adjust the counts to convert them to Watts using
+ * the duration of the measurement. Tools may use a function such as
+ * ldexp(raw_count, -32);
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/perf_event.h>
+#include <asm/cpu_device_id.h>
+#include "perf_event.h"
+
+/*
+ * RAPL energy status counters
+ */
+#define RAPL_IDX_PP0_NRG_STAT	0	/* all cores */
+#define INTEL_RAPL_PP0		0x1	/* pseudo-encoding */
+#define RAPL_IDX_PKG_NRG_STAT	1	/* entire package */
+#define INTEL_RAPL_PKG		0x2	/* pseudo-encoding */
+#define RAPL_IDX_RAM_NRG_STAT	2	/* DRAM */
+#define INTEL_RAPL_RAM		0x3	/* pseudo-encoding */
+
+/* Clients have PP0, PKG */
+#define RAPL_IDX_CLN	(1<<RAPL_IDX_PP0_NRG_STAT|\
+			 1<<RAPL_IDX_PKG_NRG_STAT)
+
+/* Servers have PP0, PKG, RAM */
+#define RAPL_IDX_SRV	(1<<RAPL_IDX_PP0_NRG_STAT|\
+			 1<<RAPL_IDX_PKG_NRG_STAT|\
+			 1<<RAPL_IDX_RAM_NRG_STAT)
+
+/*
+ * event code: LSB 8 bits, passed in attr->config
+ * any other bit is reserved
+ */
+#define RAPL_EVENT_MASK	0xFFULL
+
+#define DEFINE_RAPL_FORMAT_ATTR(_var, _name, _format)		\
+static ssize_t __rapl_##_var##_show(struct kobject *kobj,	\
+				struct kobj_attribute *attr,	\
+				char *page)			\
+{								\
+	BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE);		\
+	return sprintf(page, _format "\n");			\
+}								\
+static struct kobj_attribute format_attr_##_var =		\
+	__ATTR(_name, 0444, __rapl_##_var##_show, NULL)
+
+#define RAPL_EVENT_DESC(_name, _config)				\
+{								\
+	.attr	= __ATTR(_name, 0444, rapl_event_show, NULL),	\
+	.config	= _config,					\
+}
+
+#define RAPL_CNTR_WIDTH 32 /* 32-bit rapl counters */
+
+struct rapl_pmu {
+	spinlock_t	lock;
+	atomic_t	refcnt;
+	int		hw_unit;  /* 1/2^hw_unit Joule */
+	int		phys_id;
+	int		n_active; /* number of active events */
+	struct list_head active_list;
+};
+
+static struct pmu rapl_pmu_class;
+static cpumask_t rapl_cpu_mask;
+static int rapl_cntr_mask;
+
+static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu);
+static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu_kfree);
+
+static DEFINE_SPINLOCK(rapl_hotplug_lock);
+
+static inline u64 rapl_read_counter(struct perf_event *event)
+{
+	u64 raw;
+	rdmsrl(event->hw.event_base, raw);
+	return raw;
+}
+
+static inline u64 rapl_scale(u64 v)
+{
+	/*
+	 * scale delta to smallest unit (1/2^32)
+	 * users must then scale back: count * 1/(1e9*2^32) to get Joules
+	 * or use ldexp(count, -32).
+	 * Watts = Joules/Time delta
+	 */
+	return v << (32 - __get_cpu_var(rapl_pmu)->hw_unit);
+}
+
+static u64 rapl_event_update(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 prev_raw_count, new_raw_count;
+	s64 delta, sdelta;
+	int shift = RAPL_CNTR_WIDTH;
+
+again:
+	prev_raw_count = local64_read(&hwc->prev_count);
+	rdmsrl(event->hw.event_base, new_raw_count);
+
+	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+			    new_raw_count) != prev_raw_count) {
+		cpu_relax();
+		goto again;
+	}
+
+	/*
+	 * Now we have the new raw value and have updated the prev
+	 * timestamp already. We can now calculate the elapsed delta
+	 * (event-)time and add that to the generic event.
+	 *
+	 * Careful, not all hw sign-extends above the physical width
+	 * of the count.
+	 */
+	delta = (new_raw_count << shift) - (prev_raw_count << shift);
+	delta >>= shift;
+
+	sdelta = rapl_scale(delta);
+
+	local64_add(sdelta, &event->count);
+
+	return new_raw_count;
+}
+
+static void __rapl_pmu_event_start(struct rapl_pmu *pmu,
+				   struct perf_event *event)
+{
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	event->hw.state = 0;
+
+	list_add_tail(&event->active_entry, &pmu->active_list);
+
+	local64_set(&event->hw.prev_count, rapl_read_counter(event));
+
+	pmu->n_active++;
+}
+
+static void rapl_pmu_event_start(struct perf_event *event, int mode)
+{
+	struct rapl_pmu *pmu = __get_cpu_var(rapl_pmu);
+	unsigned long flags;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+	__rapl_pmu_event_start(pmu, event);
+	spin_unlock_irqrestore(&pmu->lock, flags);
+}
+
+static void rapl_pmu_event_stop(struct perf_event *event, int mode)
+{
+	struct rapl_pmu *pmu = __get_cpu_var(rapl_pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	/* mark event as deactivated and stopped */
+	if (!(hwc->state & PERF_HES_STOPPED)) {
+		WARN_ON_ONCE(pmu->n_active <= 0);
+		pmu->n_active--;
+
+		list_del(&event->active_entry);
+
+		WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+		hwc->state |= PERF_HES_STOPPED;
+	}
+
+	/* check if update of sw counter is necessary */
+	if ((mode & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+		/*
+		 * Drain the remaining delta count out of a event
+		 * that we are disabling:
+		 */
+		rapl_event_update(event);
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+}
+
+static int rapl_pmu_event_add(struct perf_event *event, int mode)
+{
+	struct rapl_pmu *pmu = __get_cpu_var(rapl_pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+
+	if (mode & PERF_EF_START)
+		__rapl_pmu_event_start(pmu, event);
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static void rapl_pmu_event_del(struct perf_event *event, int flags)
+{
+	rapl_pmu_event_stop(event, PERF_EF_UPDATE);
+}
+
+static int rapl_pmu_event_init(struct perf_event *event)
+{
+	u64 cfg = event->attr.config & RAPL_EVENT_MASK;
+	int bit, msr, ret = 0;
+
+	/* only look at RAPL events */
+	if (event->attr.type != rapl_pmu_class.type)
+		return -ENOENT;
+
+	/* check only supported bits are set */
+	if (event->attr.config & ~RAPL_EVENT_MASK)
+		return -EINVAL;
+
+	/*
+	 * check event is known (determines counter)
+	 */
+	switch (cfg) {
+	case INTEL_RAPL_PP0:
+		bit = RAPL_IDX_PP0_NRG_STAT;
+		msr = MSR_PP0_ENERGY_STATUS;
+		break;
+	case INTEL_RAPL_PKG:
+		bit = RAPL_IDX_PKG_NRG_STAT;
+		msr = MSR_PKG_ENERGY_STATUS;
+		break;
+	case INTEL_RAPL_RAM:
+		bit = RAPL_IDX_RAM_NRG_STAT;
+		msr = MSR_DRAM_ENERGY_STATUS;
+		break;
+	default:
+		return -EINVAL;
+	}
+	/* check event supported */
+	if (!(rapl_cntr_mask & (1 << bit)))
+		return -EINVAL;
+
+	/* unsupported modes and filters */
+	if (event->attr.exclude_user   ||
+	    event->attr.exclude_kernel ||
+	    event->attr.exclude_hv     ||
+	    event->attr.exclude_idle   ||
+	    event->attr.exclude_host   ||
+	    event->attr.exclude_guest  ||
+	    event->attr.sample_period) /* no sampling */
+		return -EINVAL;
+
+	/* must be done before validate_group */
+	event->hw.event_base = msr;
+	event->hw.config = cfg;
+	event->hw.idx = bit;
+
+	return ret;
+}
+
+static void rapl_pmu_event_read(struct perf_event *event)
+{
+	rapl_event_update(event);
+}
+
+static ssize_t rapl_get_attr_cpumask(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int n = cpulist_scnprintf(buf, PAGE_SIZE - 2, &rapl_cpu_mask);
+
+	buf[n++] = '\n';
+	buf[n] = '\0';
+	return n;
+}
+
+static DEVICE_ATTR(cpumask, S_IRUGO, rapl_get_attr_cpumask, NULL);
+
+static struct attribute *rapl_pmu_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL,
+};
+
+static struct attribute_group rapl_pmu_attr_group = {
+	.attrs = rapl_pmu_attrs,
+};
+
+EVENT_ATTR_STR(energy-cores, rapl_cores, "event=0x01");
+EVENT_ATTR_STR(energy-pkg  , rapl_pkg, "event=0x02");
+EVENT_ATTR_STR(energy-ram  , rapl_ram, "event=0x03");
+
+EVENT_ATTR_STR(energy-cores.unit, rapl_cores_unit, "Joules");
+EVENT_ATTR_STR(energy-pkg.unit  , rapl_pkg_unit, "Joules");
+EVENT_ATTR_STR(energy-ram.unit  , rapl_ram_unit, "Joules");
+
+/*
+ * we compute in 0.23 nJ increments regardless of MSR
+ */
+EVENT_ATTR_STR(energy-cores.scale, rapl_cores_scale, "2.3e-10");
+EVENT_ATTR_STR(energy-pkg.scale, rapl_pkg_scale, "2.3e-10");
+EVENT_ATTR_STR(energy-ram.scale, rapl_ram_scale, "2.3e-10");
+
+static struct attribute *rapl_events_srv_attr[] = {
+	EVENT_PTR(rapl_cores),
+	EVENT_PTR(rapl_pkg),
+	EVENT_PTR(rapl_ram),
+
+	EVENT_PTR(rapl_cores_unit),
+	EVENT_PTR(rapl_pkg_unit),
+	EVENT_PTR(rapl_ram_unit),
+
+	EVENT_PTR(rapl_cores_scale),
+	EVENT_PTR(rapl_pkg_scale),
+	EVENT_PTR(rapl_ram_scale),
+	NULL,
+};
+
+static struct attribute *rapl_events_cln_attr[] = {
+	EVENT_PTR(rapl_cores),
+	EVENT_PTR(rapl_pkg),
+
+	EVENT_PTR(rapl_cores_unit),
+	EVENT_PTR(rapl_pkg_unit),
+
+	EVENT_PTR(rapl_cores_scale),
+	EVENT_PTR(rapl_pkg_scale),
+	NULL,
+};
+
+static struct attribute_group rapl_pmu_events_group = {
+	.name = "events",
+	.attrs = NULL, /* patched at runtime */
+};
+
+DEFINE_RAPL_FORMAT_ATTR(event, event, "config:0-7");
+static struct attribute *rapl_formats_attr[] = {
+	&format_attr_event.attr,
+	NULL,
+};
+
+static struct attribute_group rapl_pmu_format_group = {
+	.name = "format",
+	.attrs = rapl_formats_attr,
+};
+
+const struct attribute_group *rapl_attr_groups[] = {
+	&rapl_pmu_attr_group,
+	&rapl_pmu_format_group,
+	&rapl_pmu_events_group,
+	NULL,
+};
+
+static struct pmu rapl_pmu_class = {
+	.attr_groups	= rapl_attr_groups,
+	.task_ctx_nr	= perf_invalid_context, /* system-wide only */
+	.event_init	= rapl_pmu_event_init,
+	.add		= rapl_pmu_event_add, /* must have */
+	.del		= rapl_pmu_event_del, /* must have */
+	.start		= rapl_pmu_event_start,
+	.stop		= rapl_pmu_event_stop,
+	.read		= rapl_pmu_event_read,
+};
+
+static void rapl_exit_cpu(int cpu)
+{
+	int i, phys_id = topology_physical_package_id(cpu);
+
+	/* if CPU not in RAPL mask, nothing to do */
+	if (!cpumask_test_and_clear_cpu(cpu, &rapl_cpu_mask))
+		return;
+
+	/* find a new cpu on same package */
+	for_each_online_cpu(i) {
+		if (i == cpu || i == 0)
+			continue;
+		if (phys_id == topology_physical_package_id(i)) {
+			cpumask_set_cpu(i, &rapl_cpu_mask);
+			break;
+		}
+	}
+
+	WARN_ON(cpumask_empty(&rapl_cpu_mask));
+}
+
+static void rapl_init_cpu(int cpu)
+{
+	int i, phys_id = topology_physical_package_id(cpu);
+
+	spin_lock(&rapl_hotplug_lock);
+
+	/* check if phys_is is already covered */
+	for_each_cpu(i, &rapl_cpu_mask) {
+		if (phys_id == topology_physical_package_id(i))
+			return;
+	}
+	/* was not found, so add it */
+	cpumask_set_cpu(cpu, &rapl_cpu_mask);
+
+	spin_unlock(&rapl_hotplug_lock);
+}
+
+static int rapl_cpu_prepare(int cpu)
+{
+	struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
+	int phys_id = topology_physical_package_id(cpu);
+
+	if (pmu)
+		return 0;
+
+	if (phys_id < 0)
+		return -1;
+
+	pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));
+	if (!pmu)
+		return -1;
+
+	spin_lock_init(&pmu->lock);
+	atomic_set(&pmu->refcnt, 1);
+
+	INIT_LIST_HEAD(&pmu->active_list);
+
+	pmu->phys_id = phys_id;
+	/*
+	 * grab power unit as: 1/2^unit Joules
+	 *
+	 * we cache in local PMU instance
+	 */
+	rdmsrl(MSR_RAPL_POWER_UNIT, pmu->hw_unit);
+	pmu->hw_unit = (pmu->hw_unit >> 8) & 0x1FULL;
+
+	/* set RAPL pmu for this cpu for now */
+	per_cpu(rapl_pmu_kfree, cpu) = NULL;
+	per_cpu(rapl_pmu, cpu) = pmu;
+
+	return 0;
+}
+
+static int rapl_cpu_starting(int cpu)
+{
+	struct rapl_pmu *pmu2;
+	struct rapl_pmu *pmu1 = per_cpu(rapl_pmu, cpu);
+	int i, phys_id = topology_physical_package_id(cpu);
+
+	if (pmu1)
+		return 0;
+
+	spin_lock(&rapl_hotplug_lock);
+
+	for_each_online_cpu(i) {
+		pmu2 = per_cpu(rapl_pmu, i);
+
+		if (!pmu2 || i == cpu)
+			continue;
+
+		if (pmu2->phys_id == phys_id) {
+			per_cpu(rapl_pmu, cpu) = pmu2;
+			per_cpu(rapl_pmu_kfree, cpu) = pmu1;
+			atomic_inc(&pmu2->refcnt);
+			break;
+		}
+	}
+	spin_unlock(&rapl_hotplug_lock);
+	return 0;
+}
+
+static int rapl_cpu_dying(int cpu)
+{
+	struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
+	struct perf_event *event, *tmp;
+
+	if (!pmu)
+		return 0;
+
+	spin_lock(&rapl_hotplug_lock);
+
+	/*
+	 * stop all syswide RAPL events on that  CPU
+	 * as a consequence also stops the hrtimer
+	 */
+	list_for_each_entry_safe(event, tmp, &pmu->active_list, active_entry) {
+		rapl_pmu_event_stop(event, PERF_EF_UPDATE);
+	}
+
+	per_cpu(rapl_pmu, cpu) = NULL;
+
+	if (atomic_dec_and_test(&pmu->refcnt))
+		kfree(pmu);
+
+	spin_unlock(&rapl_hotplug_lock);
+	return 0;
+}
+
+static int rapl_cpu_notifier(struct notifier_block *self,
+			     unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (long)hcpu;
+
+	/* allocate/free data structure for uncore box */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_UP_PREPARE:
+		rapl_cpu_prepare(cpu);
+		break;
+	case CPU_STARTING:
+		rapl_cpu_starting(cpu);
+		break;
+	case CPU_UP_CANCELED:
+	case CPU_DYING:
+		rapl_cpu_dying(cpu);
+		break;
+	case CPU_ONLINE:
+		kfree(per_cpu(rapl_pmu_kfree, cpu));
+		per_cpu(rapl_pmu_kfree, cpu) = NULL;
+		break;
+	case CPU_DEAD:
+		per_cpu(rapl_pmu, cpu) = NULL;
+		break;
+	default:
+		break;
+	}
+
+	/* select the cpu that collects uncore events */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DOWN_FAILED:
+	case CPU_STARTING:
+		rapl_init_cpu(cpu);
+		break;
+	case CPU_DOWN_PREPARE:
+		rapl_exit_cpu(cpu);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static const struct x86_cpu_id rapl_cpu_match[] = {
+	[0] = { .vendor = X86_VENDOR_INTEL, .family = 6 },
+	[1] = {},
+};
+static int __init rapl_pmu_init(void)
+{
+	struct rapl_pmu *pmu;
+	int i, cpu, ret;
+
+	/*
+	 * check for Intel processor family 6
+	 */
+	if (!x86_match_cpu(rapl_cpu_match))
+		return 0;
+
+	/* check supported CPU */
+	switch (boot_cpu_data.x86_model) {
+	case 42: /* Sandy Bridge */
+	case 58: /* Ivy Bridge */
+	case 60: /* Haswell */
+		rapl_cntr_mask = RAPL_IDX_CLN;
+		rapl_pmu_events_group.attrs = rapl_events_cln_attr;
+		break;
+	case 45: /* Sandy Bridge-EP */
+	case 62: /* IvyTown */
+		rapl_cntr_mask = RAPL_IDX_SRV;
+		rapl_pmu_events_group.attrs = rapl_events_srv_attr;
+		break;
+
+	default:
+		/* unsupported */
+		return 0;
+	}
+	get_online_cpus();
+
+	for_each_online_cpu(cpu) {
+		int phys_id = topology_physical_package_id(cpu);
+
+		/* save on prepare by only calling prepare for new phys_id */
+		for_each_cpu(i, &rapl_cpu_mask) {
+			if (phys_id == topology_physical_package_id(i)) {
+				phys_id = -1;
+				break;
+			}
+		}
+		if (phys_id < 0) {
+			pmu = per_cpu(rapl_pmu, i);
+			if (pmu) {
+				per_cpu(rapl_pmu, cpu) = pmu;
+				atomic_inc(&pmu->refcnt);
+			}
+			continue;
+		}
+		rapl_cpu_prepare(cpu);
+		cpumask_set_cpu(cpu, &rapl_cpu_mask);
+	}
+
+	perf_cpu_notifier(rapl_cpu_notifier);
+
+	ret = perf_pmu_register(&rapl_pmu_class, "power", -1);
+	WARN_ON(ret);
+	if (!ret) {
+		pr_info("RAPL PMU detected, registration failed, RAPL PMU disabled\n");
+		put_online_cpus();
+		return -1;
+	}
+
+	pmu = __get_cpu_var(rapl_pmu);
+
+	pr_info("RAPL PMU detected, hw unit 2^-%d Joules,"
+		" API unit is 2^-32 Joules,"
+		" %d fixed counters\n",
+		pmu->hw_unit,
+		hweight32(rapl_cntr_mask));
+
+	put_online_cpus();
+
+	return 0;
+}
+device_initcall(rapl_pmu_init);
-- 
1.7.9.5

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