Commit b5ab4cd5 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

perf: Per cpu-context rotation timer

Give each cpu-context its own timer so that it is a self contained
entity, this eases the way for per-pmu-per-cpu contexts as well as
provides the basic infrastructure to allow different rotation
times per pmu.

Things to look at:
 - folding the tick and these TICK_NSEC timers
 - separate task context rotation
Signed-off-by: default avatarPeter 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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b28ab83c
......@@ -861,6 +861,8 @@ struct perf_cpu_context {
struct perf_event_context *task_ctx;
int active_oncpu;
int exclusive;
u64 timer_interval;
struct hrtimer timer;
};
struct perf_output_handle {
......@@ -881,7 +883,6 @@ extern void perf_pmu_unregister(struct pmu *pmu);
extern void perf_event_task_sched_in(struct task_struct *task);
extern void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
extern void perf_event_task_tick(struct task_struct *task);
extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);
......@@ -1067,8 +1068,6 @@ perf_event_task_sched_in(struct task_struct *task) { }
static inline void
perf_event_task_sched_out(struct task_struct *task,
struct task_struct *next) { }
static inline void
perf_event_task_tick(struct task_struct *task) { }
static inline int perf_event_init_task(struct task_struct *child) { return 0; }
static inline void perf_event_exit_task(struct task_struct *child) { }
static inline void perf_event_free_task(struct task_struct *task) { }
......
......@@ -78,6 +78,25 @@ void perf_pmu_enable(struct pmu *pmu)
pmu->pmu_enable(pmu);
}
static void perf_pmu_rotate_start(void)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
if (hrtimer_active(&cpuctx->timer))
return;
__hrtimer_start_range_ns(&cpuctx->timer,
ns_to_ktime(cpuctx->timer_interval), 0,
HRTIMER_MODE_REL_PINNED, 0);
}
static void perf_pmu_rotate_stop(void)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
hrtimer_cancel(&cpuctx->timer);
}
static void get_ctx(struct perf_event_context *ctx)
{
WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
......@@ -281,6 +300,8 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
}
list_add_rcu(&event->event_entry, &ctx->event_list);
if (!ctx->nr_events)
perf_pmu_rotate_start();
ctx->nr_events++;
if (event->attr.inherit_stat)
ctx->nr_stat++;
......@@ -1383,6 +1404,12 @@ void perf_event_task_sched_in(struct task_struct *task)
ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
cpuctx->task_ctx = ctx;
/*
* Since these rotations are per-cpu, we need to ensure the
* cpu-context we got scheduled on is actually rotating.
*/
perf_pmu_rotate_start();
}
#define MAX_INTERRUPTS (~0ULL)
......@@ -1487,7 +1514,7 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
}
}
static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period)
{
struct perf_event *event;
struct hw_perf_event *hwc;
......@@ -1524,7 +1551,7 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
hwc->freq_count_stamp = now;
if (delta > 0)
perf_adjust_period(event, TICK_NSEC, delta);
perf_adjust_period(event, period, delta);
}
raw_spin_unlock(&ctx->lock);
}
......@@ -1542,30 +1569,39 @@ static void rotate_ctx(struct perf_event_context *ctx)
raw_spin_unlock(&ctx->lock);
}
void perf_event_task_tick(struct task_struct *curr)
/*
* Cannot race with ->pmu_rotate_start() because this is ran from hardirq
* context, and ->pmu_rotate_start() is called with irqs disabled (both are
* cpu affine, so there are no SMP races).
*/
static enum hrtimer_restart perf_event_context_tick(struct hrtimer *timer)
{
enum hrtimer_restart restart = HRTIMER_NORESTART;
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
int rotate = 0;
if (!atomic_read(&nr_events))
return;
cpuctx = container_of(timer, struct perf_cpu_context, timer);
cpuctx = &__get_cpu_var(perf_cpu_context);
if (cpuctx->ctx.nr_events &&
cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
rotate = 1;
if (cpuctx->ctx.nr_events) {
restart = HRTIMER_RESTART;
if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
rotate = 1;
}
ctx = curr->perf_event_ctxp;
if (ctx && ctx->nr_events && ctx->nr_events != ctx->nr_active)
rotate = 1;
ctx = current->perf_event_ctxp;
if (ctx && ctx->nr_events) {
restart = HRTIMER_RESTART;
if (ctx->nr_events != ctx->nr_active)
rotate = 1;
}
perf_ctx_adjust_freq(&cpuctx->ctx);
perf_ctx_adjust_freq(&cpuctx->ctx, cpuctx->timer_interval);
if (ctx)
perf_ctx_adjust_freq(ctx);
perf_ctx_adjust_freq(ctx, cpuctx->timer_interval);
if (!rotate)
return;
goto done;
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
if (ctx)
......@@ -1577,7 +1613,12 @@ void perf_event_task_tick(struct task_struct *curr)
cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
if (ctx)
task_ctx_sched_in(curr, EVENT_FLEXIBLE);
task_ctx_sched_in(current, EVENT_FLEXIBLE);
done:
hrtimer_forward_now(timer, ns_to_ktime(cpuctx->timer_interval));
return restart;
}
static int event_enable_on_exec(struct perf_event *event,
......@@ -4786,7 +4827,7 @@ static void perf_swevent_start_hrtimer(struct perf_event *event)
}
__hrtimer_start_range_ns(&hwc->hrtimer,
ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
HRTIMER_MODE_REL_PINNED, 0);
}
}
......@@ -5904,6 +5945,9 @@ static void __init perf_event_init_all_cpus(void)
cpuctx = &per_cpu(perf_cpu_context, cpu);
__perf_event_init_context(&cpuctx->ctx, NULL);
cpuctx->timer_interval = TICK_NSEC;
hrtimer_init(&cpuctx->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cpuctx->timer.function = perf_event_context_tick;
}
}
......@@ -5934,6 +5978,8 @@ static void __perf_event_exit_cpu(void *info)
struct perf_event_context *ctx = &cpuctx->ctx;
struct perf_event *event, *tmp;
perf_pmu_rotate_stop();
list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
__perf_event_remove_from_context(event);
list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
......
......@@ -3578,8 +3578,6 @@ void scheduler_tick(void)
curr->sched_class->task_tick(rq, curr, 0);
raw_spin_unlock(&rq->lock);
perf_event_task_tick(curr);
#ifdef CONFIG_SMP
rq->idle_at_tick = idle_cpu(cpu);
trigger_load_balance(rq, cpu);
......
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