perf: Rework the PMU methods
Replace pmu::{enable,disable,start,stop,unthrottle} with
pmu::{add,del,start,stop}, all of which take a flags argument.
The new interface extends the capability to stop a counter while
keeping it scheduled on the PMU. We replace the throttled state with
the generic stopped state.
This also allows us to efficiently stop/start counters over certain
code paths (like IRQ handlers).
It also allows scheduling a counter without it starting, allowing for
a generic frozen state (useful for rotating stopped counters).
The stopped state is implemented in two different ways, depending on
how the architecture implemented the throttled state:
1) We disable the counter:
a) the pmu has per-counter enable bits, we flip that
b) we program a NOP event, preserving the counter state
2) We store the counter state and ignore all read/overflow events
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 1a6cdbf..3bace4f 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -424,7 +424,7 @@
event->state = PERF_EVENT_STATE_OFF;
}
event->tstamp_stopped = ctx->time;
- event->pmu->disable(event);
+ event->pmu->del(event, 0);
event->oncpu = -1;
if (!is_software_event(event))
@@ -649,7 +649,7 @@
*/
smp_wmb();
- if (event->pmu->enable(event)) {
+ if (event->pmu->add(event, PERF_EF_START)) {
event->state = PERF_EVENT_STATE_INACTIVE;
event->oncpu = -1;
return -EAGAIN;
@@ -1482,22 +1482,6 @@
return div64_u64(dividend, divisor);
}
-static void perf_event_stop(struct perf_event *event)
-{
- if (!event->pmu->stop)
- return event->pmu->disable(event);
-
- return event->pmu->stop(event);
-}
-
-static int perf_event_start(struct perf_event *event)
-{
- if (!event->pmu->start)
- return event->pmu->enable(event);
-
- return event->pmu->start(event);
-}
-
static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
{
struct hw_perf_event *hwc = &event->hw;
@@ -1517,9 +1501,9 @@
hwc->sample_period = sample_period;
if (local64_read(&hwc->period_left) > 8*sample_period) {
- perf_event_stop(event);
+ event->pmu->stop(event, PERF_EF_UPDATE);
local64_set(&hwc->period_left, 0);
- perf_event_start(event);
+ event->pmu->start(event, PERF_EF_RELOAD);
}
}
@@ -1548,7 +1532,7 @@
*/
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(event, 1);
- event->pmu->unthrottle(event);
+ event->pmu->start(event, 0);
}
if (!event->attr.freq || !event->attr.sample_freq)
@@ -2506,6 +2490,9 @@
static int perf_event_index(struct perf_event *event)
{
+ if (event->hw.state & PERF_HES_STOPPED)
+ return 0;
+
if (event->state != PERF_EVENT_STATE_ACTIVE)
return 0;
@@ -4120,8 +4107,6 @@
struct hw_perf_event *hwc = &event->hw;
int ret = 0;
- throttle = (throttle && event->pmu->unthrottle != NULL);
-
if (!throttle) {
hwc->interrupts++;
} else {
@@ -4246,7 +4231,7 @@
}
}
-static void perf_swevent_add(struct perf_event *event, u64 nr,
+static void perf_swevent_event(struct perf_event *event, u64 nr,
int nmi, struct perf_sample_data *data,
struct pt_regs *regs)
{
@@ -4272,6 +4257,9 @@
static int perf_exclude_event(struct perf_event *event,
struct pt_regs *regs)
{
+ if (event->hw.state & PERF_HES_STOPPED)
+ return 0;
+
if (regs) {
if (event->attr.exclude_user && user_mode(regs))
return 1;
@@ -4371,7 +4359,7 @@
hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
if (perf_swevent_match(event, type, event_id, data, regs))
- perf_swevent_add(event, nr, nmi, data, regs);
+ perf_swevent_event(event, nr, nmi, data, regs);
}
end:
rcu_read_unlock();
@@ -4415,7 +4403,7 @@
{
}
-static int perf_swevent_enable(struct perf_event *event)
+static int perf_swevent_add(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
struct perf_cpu_context *cpuctx;
@@ -4428,6 +4416,8 @@
perf_swevent_set_period(event);
}
+ hwc->state = !(flags & PERF_EF_START);
+
head = find_swevent_head(cpuctx, event);
if (WARN_ON_ONCE(!head))
return -EINVAL;
@@ -4437,18 +4427,19 @@
return 0;
}
-static void perf_swevent_disable(struct perf_event *event)
+static void perf_swevent_del(struct perf_event *event, int flags)
{
hlist_del_rcu(&event->hlist_entry);
}
-static void perf_swevent_void(struct perf_event *event)
+static void perf_swevent_start(struct perf_event *event, int flags)
{
+ event->hw.state = 0;
}
-static int perf_swevent_int(struct perf_event *event)
+static void perf_swevent_stop(struct perf_event *event, int flags)
{
- return 0;
+ event->hw.state = PERF_HES_STOPPED;
}
/* Deref the hlist from the update side */
@@ -4604,12 +4595,11 @@
static struct pmu perf_swevent = {
.event_init = perf_swevent_init,
- .enable = perf_swevent_enable,
- .disable = perf_swevent_disable,
- .start = perf_swevent_int,
- .stop = perf_swevent_void,
+ .add = perf_swevent_add,
+ .del = perf_swevent_del,
+ .start = perf_swevent_start,
+ .stop = perf_swevent_stop,
.read = perf_swevent_read,
- .unthrottle = perf_swevent_void, /* hwc->interrupts already reset */
};
#ifdef CONFIG_EVENT_TRACING
@@ -4657,7 +4647,7 @@
hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
if (perf_tp_event_match(event, &data, regs))
- perf_swevent_add(event, count, 1, &data, regs);
+ perf_swevent_event(event, count, 1, &data, regs);
}
perf_swevent_put_recursion_context(rctx);
@@ -4696,12 +4686,11 @@
static struct pmu perf_tracepoint = {
.event_init = perf_tp_event_init,
- .enable = perf_trace_enable,
- .disable = perf_trace_disable,
- .start = perf_swevent_int,
- .stop = perf_swevent_void,
+ .add = perf_trace_add,
+ .del = perf_trace_del,
+ .start = perf_swevent_start,
+ .stop = perf_swevent_stop,
.read = perf_swevent_read,
- .unthrottle = perf_swevent_void,
};
static inline void perf_tp_register(void)
@@ -4757,8 +4746,8 @@
perf_sample_data_init(&sample, bp->attr.bp_addr);
- if (!perf_exclude_event(bp, regs))
- perf_swevent_add(bp, 1, 1, &sample, regs);
+ if (!bp->hw.state && !perf_exclude_event(bp, regs))
+ perf_swevent_event(bp, 1, 1, &sample, regs);
}
#endif
@@ -4834,30 +4823,37 @@
static void cpu_clock_event_update(struct perf_event *event)
{
- int cpu = raw_smp_processor_id();
s64 prev;
u64 now;
- now = cpu_clock(cpu);
+ now = local_clock();
prev = local64_xchg(&event->hw.prev_count, now);
local64_add(now - prev, &event->count);
}
-static int cpu_clock_event_enable(struct perf_event *event)
+static void cpu_clock_event_start(struct perf_event *event, int flags)
{
- struct hw_perf_event *hwc = &event->hw;
- int cpu = raw_smp_processor_id();
-
- local64_set(&hwc->prev_count, cpu_clock(cpu));
+ local64_set(&event->hw.prev_count, local_clock());
perf_swevent_start_hrtimer(event);
+}
+
+static void cpu_clock_event_stop(struct perf_event *event, int flags)
+{
+ perf_swevent_cancel_hrtimer(event);
+ cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_add(struct perf_event *event, int flags)
+{
+ if (flags & PERF_EF_START)
+ cpu_clock_event_start(event, flags);
return 0;
}
-static void cpu_clock_event_disable(struct perf_event *event)
+static void cpu_clock_event_del(struct perf_event *event, int flags)
{
- perf_swevent_cancel_hrtimer(event);
- cpu_clock_event_update(event);
+ cpu_clock_event_stop(event, flags);
}
static void cpu_clock_event_read(struct perf_event *event)
@@ -4878,8 +4874,10 @@
static struct pmu perf_cpu_clock = {
.event_init = cpu_clock_event_init,
- .enable = cpu_clock_event_enable,
- .disable = cpu_clock_event_disable,
+ .add = cpu_clock_event_add,
+ .del = cpu_clock_event_del,
+ .start = cpu_clock_event_start,
+ .stop = cpu_clock_event_stop,
.read = cpu_clock_event_read,
};
@@ -4897,25 +4895,29 @@
local64_add(delta, &event->count);
}
-static int task_clock_event_enable(struct perf_event *event)
+static void task_clock_event_start(struct perf_event *event, int flags)
{
- struct hw_perf_event *hwc = &event->hw;
- u64 now;
-
- now = event->ctx->time;
-
- local64_set(&hwc->prev_count, now);
-
+ local64_set(&event->hw.prev_count, event->ctx->time);
perf_swevent_start_hrtimer(event);
+}
+
+static void task_clock_event_stop(struct perf_event *event, int flags)
+{
+ perf_swevent_cancel_hrtimer(event);
+ task_clock_event_update(event, event->ctx->time);
+}
+
+static int task_clock_event_add(struct perf_event *event, int flags)
+{
+ if (flags & PERF_EF_START)
+ task_clock_event_start(event, flags);
return 0;
}
-static void task_clock_event_disable(struct perf_event *event)
+static void task_clock_event_del(struct perf_event *event, int flags)
{
- perf_swevent_cancel_hrtimer(event);
- task_clock_event_update(event, event->ctx->time);
-
+ task_clock_event_stop(event, PERF_EF_UPDATE);
}
static void task_clock_event_read(struct perf_event *event)
@@ -4947,8 +4949,10 @@
static struct pmu perf_task_clock = {
.event_init = task_clock_event_init,
- .enable = task_clock_event_enable,
- .disable = task_clock_event_disable,
+ .add = task_clock_event_add,
+ .del = task_clock_event_del,
+ .start = task_clock_event_start,
+ .stop = task_clock_event_stop,
.read = task_clock_event_read,
};