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perf/x86/intel/rapl: Convert it to a per package facility
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RAPL is a per package facility and we already have a mechanism for a dedicated
per package reader. So there is no point to have multiple CPUs doing the
same. The current implementation actually starts two timers on two CPUs if one
does:

	perf stat -C1,2 -e -e power/energy-pkg ....

which makes the whole concept of 1 reader per package moot.

What's worse is that the above returns the double of the actual energy
consumption, but that's a different problem to address and cannot be solved by
removing the pointless per cpuness of that mechanism.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Harish Chegondi <harish.chegondi@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20160222221012.845369524@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Thomas Gleixner authored and Ingo Molnar committed Feb 29, 2016
1 parent 8a6d2f8 commit 9de8d68
Showing 1 changed file with 86 additions and 108 deletions.
194 changes: 86 additions & 108 deletions arch/x86/events/intel/rapl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,15 +129,23 @@ struct rapl_pmu {
struct hrtimer hrtimer;
};

struct rapl_pmus {
struct pmu pmu;
unsigned int maxpkg;
struct rapl_pmu *pmus[];
};

/* 1/2^hw_unit Joule */
static int rapl_hw_unit[NR_RAPL_DOMAINS] __read_mostly;
static struct pmu rapl_pmu_class;
static struct rapl_pmus *rapl_pmus;
static cpumask_t rapl_cpu_mask;
static int rapl_cntr_mask;
static unsigned int rapl_cntr_mask;
static u64 rapl_timer_ms;

static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu);
static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu_to_free);
static inline struct rapl_pmu *cpu_to_rapl_pmu(unsigned int cpu)
{
return rapl_pmus->pmus[topology_logical_package_id(cpu)];
}

static inline u64 rapl_read_counter(struct perf_event *event)
{
Expand Down Expand Up @@ -317,12 +325,12 @@ static void rapl_pmu_event_del(struct perf_event *event, int flags)

static int rapl_pmu_event_init(struct perf_event *event)
{
struct rapl_pmu *pmu = __this_cpu_read(rapl_pmu);
u64 cfg = event->attr.config & RAPL_EVENT_MASK;
int bit, msr, ret = 0;
struct rapl_pmu *pmu;

/* only look at RAPL events */
if (event->attr.type != rapl_pmu_class.type)
if (event->attr.type != rapl_pmus->pmu.type)
return -ENOENT;

/* check only supported bits are set */
Expand Down Expand Up @@ -370,6 +378,7 @@ static int rapl_pmu_event_init(struct perf_event *event)
return -EINVAL;

/* must be done before validate_group */
pmu = cpu_to_rapl_pmu(event->cpu);
event->cpu = pmu->cpu;
event->pmu_private = pmu;
event->hw.event_base = msr;
Expand Down Expand Up @@ -502,116 +511,62 @@ const struct attribute_group *rapl_attr_groups[] = {
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_cpu_exit(int cpu)
{
struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
int i, phys_id = topology_physical_package_id(cpu);
int target = -1;
struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
int target;

/* find a new cpu on same package */
for_each_online_cpu(i) {
if (i == cpu)
continue;
if (phys_id == topology_physical_package_id(i)) {
target = i;
break;
}
}
/*
* clear cpu from cpumask
* if was set in cpumask and still some cpu on package,
* then move to new cpu
*/
if (cpumask_test_and_clear_cpu(cpu, &rapl_cpu_mask) && target >= 0)
cpumask_set_cpu(target, &rapl_cpu_mask);
/* Check if exiting cpu is used for collecting rapl events */
if (!cpumask_test_and_clear_cpu(cpu, &rapl_cpu_mask))
return;

WARN_ON(cpumask_empty(&rapl_cpu_mask));
/*
* migrate events and context to new cpu
*/
if (target >= 0)
perf_pmu_migrate_context(pmu->pmu, cpu, target);
pmu->cpu = -1;
/* Find a new cpu to collect rapl events */
target = cpumask_any_but(topology_core_cpumask(cpu), cpu);

/* cancel overflow polling timer for CPU */
hrtimer_cancel(&pmu->hrtimer);
/* Migrate rapl events to the new target */
if (target < nr_cpu_ids) {
cpumask_set_cpu(target, &rapl_cpu_mask);
pmu->cpu = target;
perf_pmu_migrate_context(pmu->pmu, cpu, target);
}
}

static void rapl_cpu_init(int cpu)
{
int i, phys_id = topology_physical_package_id(cpu);
struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
int target;

/*
* Check if there is an online cpu in the package which collects rapl
* events already.
*/
target = cpumask_any_and(&rapl_cpu_mask, topology_core_cpumask(cpu));
if (target < nr_cpu_ids)
return;

/* 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);
pmu->cpu = cpu;
}

static int rapl_cpu_prepare(int cpu)
{
struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
int phys_id = topology_physical_package_id(cpu);
struct rapl_pmu *pmu = cpu_to_rapl_pmu(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;
raw_spin_lock_init(&pmu->lock);
return -ENOMEM;

raw_spin_lock_init(&pmu->lock);
INIT_LIST_HEAD(&pmu->active_list);

pmu->pmu = &rapl_pmu_class;
pmu->cpu = cpu;

pmu->pmu = &rapl_pmus->pmu;
pmu->timer_interval = ms_to_ktime(rapl_timer_ms);

pmu->cpu = -1;
rapl_hrtimer_init(pmu);

/* set RAPL pmu for this cpu for now */
per_cpu(rapl_pmu, cpu) = pmu;
per_cpu(rapl_pmu_to_free, cpu) = NULL;

return 0;
}

static void rapl_cpu_kfree(int cpu)
{
struct rapl_pmu *pmu = per_cpu(rapl_pmu_to_free, cpu);

kfree(pmu);

per_cpu(rapl_pmu_to_free, cpu) = NULL;
}

static int rapl_cpu_dying(int cpu)
{
struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);

if (!pmu)
return 0;

per_cpu(rapl_pmu, cpu) = NULL;

per_cpu(rapl_pmu_to_free, cpu) = pmu;

rapl_pmus->pmus[topology_logical_package_id(cpu)] = pmu;
return 0;
}

Expand All @@ -624,24 +579,16 @@ static int rapl_cpu_notifier(struct notifier_block *self,
case CPU_UP_PREPARE:
rapl_cpu_prepare(cpu);
break;
case CPU_STARTING:
rapl_cpu_init(cpu);
break;
case CPU_UP_CANCELED:
case CPU_DYING:
rapl_cpu_dying(cpu);
break;

case CPU_DOWN_FAILED:
case CPU_ONLINE:
case CPU_DEAD:
rapl_cpu_kfree(cpu);
rapl_cpu_init(cpu);
break;

case CPU_DOWN_PREPARE:
rapl_cpu_exit(cpu);
break;
default:
break;
}

return NOTIFY_OK;
}

Expand Down Expand Up @@ -703,10 +650,14 @@ static void __init rapl_advertise(void)

static int __init rapl_prepare_cpus(void)
{
unsigned int cpu;
unsigned int cpu, pkg;
int ret;

for_each_online_cpu(cpu) {
pkg = topology_logical_package_id(cpu);
if (rapl_pmus->pmus[pkg])
continue;

ret = rapl_cpu_prepare(cpu);
if (ret)
return ret;
Expand All @@ -717,10 +668,33 @@ static int __init rapl_prepare_cpus(void)

static void __init cleanup_rapl_pmus(void)
{
int cpu;
int i;

for (i = 0; i < rapl_pmus->maxpkg; i++)
kfree(rapl_pmus->pmus + i);
kfree(rapl_pmus);
}

for_each_online_cpu(cpu)
kfree(per_cpu(rapl_pmu, cpu));
static int __init init_rapl_pmus(void)
{
int maxpkg = topology_max_packages();
size_t size;

size = sizeof(*rapl_pmus) + maxpkg * sizeof(struct rapl_pmu *);
rapl_pmus = kzalloc(size, GFP_KERNEL);
if (!rapl_pmus)
return -ENOMEM;

rapl_pmus->maxpkg = maxpkg;
rapl_pmus->pmu.attr_groups = rapl_attr_groups;
rapl_pmus->pmu.task_ctx_nr = perf_invalid_context;
rapl_pmus->pmu.event_init = rapl_pmu_event_init;
rapl_pmus->pmu.add = rapl_pmu_event_add;
rapl_pmus->pmu.del = rapl_pmu_event_del;
rapl_pmus->pmu.start = rapl_pmu_event_start;
rapl_pmus->pmu.stop = rapl_pmu_event_stop;
rapl_pmus->pmu.read = rapl_pmu_event_read;
return 0;
}

static const struct x86_cpu_id rapl_cpu_match[] __initconst = {
Expand Down Expand Up @@ -771,13 +745,17 @@ static int __init rapl_pmu_init(void)
if (ret)
return ret;

ret = init_rapl_pmus();
if (ret)
return ret;

cpu_notifier_register_begin();

ret = rapl_prepare_cpus();
if (ret)
goto out;

ret = perf_pmu_register(&rapl_pmu_class, "power", -1);
ret = perf_pmu_register(&rapl_pmus->pmu, "power", -1);
if (ret)
goto out;

Expand Down

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