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Date: Fri, 15 May 2009 14:43:35 GMT
From: tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, acme@...hat.com, paulus@...ba.org,
hpa@...or.com, mingo@...hat.com, a.p.zijlstra@...llo.nl,
tglx@...utronix.de, cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: frequency based adaptive irq_period
Commit-ID: 60db5e09c13109b13830cc9dcae688003fd39e79
Gitweb: http://git.kernel.org/tip/60db5e09c13109b13830cc9dcae688003fd39e79
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Fri, 15 May 2009 15:19:28 +0200
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 15 May 2009 15:26:56 +0200
perf_counter: frequency based adaptive irq_period
Instead of specifying the irq_period for a counter, provide a target interrupt
frequency and dynamically adapt the irq_period to match this frequency.
[ Impact: new perf-counter attribute/feature ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
LKML-Reference: <20090515132018.646195868@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
arch/powerpc/kernel/perf_counter.c | 13 +++----
arch/x86/kernel/cpu/perf_counter.c | 9 ++---
include/linux/perf_counter.h | 10 ++++-
kernel/perf_counter.c | 63 +++++++++++++++++++++++++++++-------
4 files changed, 68 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c
index bb1b463..db8d5ca 100644
--- a/arch/powerpc/kernel/perf_counter.c
+++ b/arch/powerpc/kernel/perf_counter.c
@@ -534,7 +534,7 @@ void hw_perf_enable(void)
continue;
}
val = 0;
- if (counter->hw_event.irq_period) {
+ if (counter->hw.irq_period) {
left = atomic64_read(&counter->hw.period_left);
if (left < 0x80000000L)
val = 0x80000000L - left;
@@ -829,8 +829,6 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
if (!ppmu)
return ERR_PTR(-ENXIO);
- if ((s64)counter->hw_event.irq_period < 0)
- return ERR_PTR(-EINVAL);
if (!perf_event_raw(&counter->hw_event)) {
ev = perf_event_id(&counter->hw_event);
if (ev >= ppmu->n_generic || ppmu->generic_events[ev] == 0)
@@ -901,7 +899,7 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
counter->hw.config = events[n];
counter->hw.counter_base = cflags[n];
- atomic64_set(&counter->hw.period_left, counter->hw_event.irq_period);
+ atomic64_set(&counter->hw.period_left, counter->hw.irq_period);
/*
* See if we need to reserve the PMU.
@@ -934,6 +932,7 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
static void record_and_restart(struct perf_counter *counter, long val,
struct pt_regs *regs, int nmi)
{
+ u64 period = counter->hw.irq_period;
s64 prev, delta, left;
int record = 0;
@@ -948,11 +947,11 @@ static void record_and_restart(struct perf_counter *counter, long val,
*/
val = 0;
left = atomic64_read(&counter->hw.period_left) - delta;
- if (counter->hw_event.irq_period) {
+ if (period) {
if (left <= 0) {
- left += counter->hw_event.irq_period;
+ left += period;
if (left <= 0)
- left = counter->hw_event.irq_period;
+ left = period;
record = 1;
}
if (left < 0x80000000L)
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 5a7f718..886dcf3 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -286,11 +286,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
hwc->nmi = 1;
}
- hwc->irq_period = hw_event->irq_period;
- if ((s64)hwc->irq_period <= 0 || hwc->irq_period > x86_pmu.max_period)
- hwc->irq_period = x86_pmu.max_period;
-
- atomic64_set(&hwc->period_left, hwc->irq_period);
+ atomic64_set(&hwc->period_left,
+ min(x86_pmu.max_period, hwc->irq_period));
/*
* Raw event type provide the config in the event structure
@@ -458,7 +455,7 @@ x86_perf_counter_set_period(struct perf_counter *counter,
struct hw_perf_counter *hwc, int idx)
{
s64 left = atomic64_read(&hwc->period_left);
- s64 period = hwc->irq_period;
+ s64 period = min(x86_pmu.max_period, hwc->irq_period);
int err;
/*
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index e543ecc..004b6e1 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -130,7 +130,11 @@ struct perf_counter_hw_event {
*/
__u64 config;
- __u64 irq_period;
+ union {
+ __u64 irq_period;
+ __u64 irq_freq;
+ };
+
__u32 record_type;
__u32 read_format;
@@ -146,8 +150,9 @@ struct perf_counter_hw_event {
mmap : 1, /* include mmap data */
munmap : 1, /* include munmap data */
comm : 1, /* include comm data */
+ freq : 1, /* use freq, not period */
- __reserved_1 : 52;
+ __reserved_1 : 51;
__u32 extra_config_len;
__u32 wakeup_events; /* wakeup every n events */
@@ -337,6 +342,7 @@ struct hw_perf_counter {
atomic64_t prev_count;
u64 irq_period;
atomic64_t period_left;
+ u64 interrupts;
#endif
};
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 93f4a0e..0ad1db4 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1046,6 +1046,38 @@ int perf_counter_task_enable(void)
return 0;
}
+void perf_adjust_freq(struct perf_counter_context *ctx)
+{
+ struct perf_counter *counter;
+ u64 irq_period;
+ u64 events, period;
+ s64 delta;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(counter, &ctx->counter_list, list_entry) {
+ if (counter->state != PERF_COUNTER_STATE_ACTIVE)
+ continue;
+
+ if (!counter->hw_event.freq || !counter->hw_event.irq_freq)
+ continue;
+
+ events = HZ * counter->hw.interrupts * counter->hw.irq_period;
+ period = div64_u64(events, counter->hw_event.irq_freq);
+
+ delta = (s64)(1 + period - counter->hw.irq_period);
+ delta >>= 1;
+
+ irq_period = counter->hw.irq_period + delta;
+
+ if (!irq_period)
+ irq_period = 1;
+
+ counter->hw.irq_period = irq_period;
+ counter->hw.interrupts = 0;
+ }
+ spin_unlock(&ctx->lock);
+}
+
/*
* Round-robin a context's counters:
*/
@@ -1081,6 +1113,9 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu)
cpuctx = &per_cpu(perf_cpu_context, cpu);
ctx = &curr->perf_counter_ctx;
+ perf_adjust_freq(&cpuctx->ctx);
+ perf_adjust_freq(ctx);
+
perf_counter_cpu_sched_out(cpuctx);
__perf_counter_task_sched_out(ctx);
@@ -2382,6 +2417,8 @@ int perf_counter_overflow(struct perf_counter *counter,
int events = atomic_read(&counter->event_limit);
int ret = 0;
+ counter->hw.interrupts++;
+
/*
* XXX event_limit might not quite work as expected on inherited
* counters
@@ -2450,6 +2487,7 @@ static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer)
enum hrtimer_restart ret = HRTIMER_RESTART;
struct perf_counter *counter;
struct pt_regs *regs;
+ u64 period;
counter = container_of(hrtimer, struct perf_counter, hw.hrtimer);
counter->pmu->read(counter);
@@ -2468,7 +2506,8 @@ static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer)
ret = HRTIMER_NORESTART;
}
- hrtimer_forward_now(hrtimer, ns_to_ktime(counter->hw.irq_period));
+ period = max_t(u64, 10000, counter->hw.irq_period);
+ hrtimer_forward_now(hrtimer, ns_to_ktime(period));
return ret;
}
@@ -2629,8 +2668,9 @@ static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hwc->hrtimer.function = perf_swcounter_hrtimer;
if (hwc->irq_period) {
+ u64 period = max_t(u64, 10000, hwc->irq_period);
__hrtimer_start_range_ns(&hwc->hrtimer,
- ns_to_ktime(hwc->irq_period), 0,
+ ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
}
@@ -2679,8 +2719,9 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter)
hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hwc->hrtimer.function = perf_swcounter_hrtimer;
if (hwc->irq_period) {
+ u64 period = max_t(u64, 10000, hwc->irq_period);
__hrtimer_start_range_ns(&hwc->hrtimer,
- ns_to_ktime(hwc->irq_period), 0,
+ ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
}
@@ -2811,9 +2852,7 @@ static const struct pmu *tp_perf_counter_init(struct perf_counter *counter)
static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
{
- struct perf_counter_hw_event *hw_event = &counter->hw_event;
const struct pmu *pmu = NULL;
- struct hw_perf_counter *hwc = &counter->hw;
/*
* Software counters (currently) can't in general distinguish
@@ -2826,8 +2865,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
case PERF_COUNT_CPU_CLOCK:
pmu = &perf_ops_cpu_clock;
- if (hw_event->irq_period && hw_event->irq_period < 10000)
- hw_event->irq_period = 10000;
break;
case PERF_COUNT_TASK_CLOCK:
/*
@@ -2839,8 +2876,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
else
pmu = &perf_ops_cpu_clock;
- if (hw_event->irq_period && hw_event->irq_period < 10000)
- hw_event->irq_period = 10000;
break;
case PERF_COUNT_PAGE_FAULTS:
case PERF_COUNT_PAGE_FAULTS_MIN:
@@ -2854,9 +2889,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
break;
}
- if (pmu)
- hwc->irq_period = hw_event->irq_period;
-
return pmu;
}
@@ -2872,6 +2904,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
{
const struct pmu *pmu;
struct perf_counter *counter;
+ struct hw_perf_counter *hwc;
long err;
counter = kzalloc(sizeof(*counter), gfpflags);
@@ -2907,6 +2940,12 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
pmu = NULL;
+ hwc = &counter->hw;
+ if (hw_event->freq && hw_event->irq_freq)
+ hwc->irq_period = TICK_NSEC / hw_event->irq_freq;
+ else
+ hwc->irq_period = hw_event->irq_period;
+
/*
* we currently do not support PERF_RECORD_GROUP on inherited counters
*/
--
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