Commit 95cdd2e7 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perfcounters: enable lowlevel pmc code to schedule counters 



Allow lowlevel ->enable() op to return an error if a counter can not be
added. This can be used to handle counter constraints.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 78b6084c

arch/x86/kernel/cpu/perf_counter.c

+5 −1
Original line number Diff line number Diff line
@@ -244,7 +244,7 @@ static int fixed_mode_idx(struct hw_perf_counter *hwc) 
/*

 * Find a PMC slot for the freshly enabled / scheduled in counter:

 */

static void pmc_generic_enable(struct perf_counter *counter)

static int pmc_generic_enable(struct perf_counter *counter)

{

	struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

	struct hw_perf_counter *hwc = &counter->hw;
@@ -253,6 +253,8 @@ static void pmc_generic_enable(struct perf_counter *counter) 
	/* Try to get the previous counter again */

	if (test_and_set_bit(idx, cpuc->used)) {

		idx = find_first_zero_bit(cpuc->used, nr_counters_generic);

		if (idx == nr_counters_generic)

			return -EAGAIN;

		set_bit(idx, cpuc->used);

		hwc->idx = idx;

	}
@@ -265,6 +267,8 @@ static void pmc_generic_enable(struct perf_counter *counter) 


	__hw_perf_counter_set_period(counter, hwc, idx);

	__pmc_generic_enable(counter, hwc, idx);



	return 0;

}



void perf_counter_print_debug(void)

include/linux/perf_counter.h

+1 −1
Original line number Diff line number Diff line
@@ -128,7 +128,7 @@ struct perf_counter; 
 * struct hw_perf_counter_ops - performance counter hw ops

 */

struct hw_perf_counter_ops {

	void (*enable)			(struct perf_counter *counter);

	int (*enable)			(struct perf_counter *counter);

	void (*disable)			(struct perf_counter *counter);

	void (*read)			(struct perf_counter *counter);

};

kernel/perf_counter.c

+45 −17
Original line number Diff line number Diff line
@@ -355,21 +355,25 @@ void perf_counter_task_sched_out(struct task_struct *task, int cpu) 
	cpuctx->task_ctx = NULL;

}



static void

static int

counter_sched_in(struct perf_counter *counter,

		 struct perf_cpu_context *cpuctx,

		 struct perf_counter_context *ctx,

		 int cpu)

{

	if (counter->state == PERF_COUNTER_STATE_OFF)

		return;

		return 0;



	if (counter->hw_ops->enable(counter))

		return -EAGAIN;



	counter->hw_ops->enable(counter);

	counter->state = PERF_COUNTER_STATE_ACTIVE;

	counter->oncpu = cpu;	/* TODO: put 'cpu' into cpuctx->cpu */



	cpuctx->active_oncpu++;

	ctx->nr_active++;



	return 0;

}



static int
@@ -378,20 +382,38 @@ group_sched_in(struct perf_counter *group_counter, 
	       struct perf_counter_context *ctx,

	       int cpu)

{

	struct perf_counter *counter;

	int was_group = 0;

	struct perf_counter *counter, *partial_group;

	int ret = 0;



	counter_sched_in(group_counter, cpuctx, ctx, cpu);

	if (counter_sched_in(group_counter, cpuctx, ctx, cpu))

		return -EAGAIN;



	/*

	 * Schedule in siblings as one group (if any):

	 */

	list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {

		counter_sched_in(counter, cpuctx, ctx, cpu);

		was_group = 1;

		if (counter_sched_in(counter, cpuctx, ctx, cpu)) {

			partial_group = counter;

			goto group_error;

		}

		ret = -EAGAIN;

	}



	return ret;



group_error:

	/*

	 * Groups can be scheduled in as one unit only, so undo any

	 * partial group before returning:

	 */

	list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {

		if (counter == partial_group)

			break;

		counter_sched_out(counter, cpuctx, ctx);

	}

	counter_sched_out(group_counter, cpuctx, ctx);



	return was_group;

	return -EAGAIN;

}



/*
@@ -416,9 +438,6 @@ void perf_counter_task_sched_in(struct task_struct *task, int cpu) 


	spin_lock(&ctx->lock);

	list_for_each_entry(counter, &ctx->counter_list, list_entry) {

		if (ctx->nr_active == cpuctx->max_pertask)

			break;



		/*

		 * Listen to the 'cpu' scheduling filter constraint

		 * of counters:
@@ -856,8 +875,9 @@ static const struct file_operations perf_fops = { 
	.poll			= perf_poll,

};



static void cpu_clock_perf_counter_enable(struct perf_counter *counter)

static int cpu_clock_perf_counter_enable(struct perf_counter *counter)

{

	return 0;

}



static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
@@ -913,11 +933,13 @@ static void task_clock_perf_counter_read(struct perf_counter *counter) 
	task_clock_perf_counter_update(counter, now);

}



static void task_clock_perf_counter_enable(struct perf_counter *counter)

static int task_clock_perf_counter_enable(struct perf_counter *counter)

{

	u64 now = task_clock_perf_counter_val(counter, 0);



	atomic64_set(&counter->hw.prev_count, now);



	return 0;

}



static void task_clock_perf_counter_disable(struct perf_counter *counter)
@@ -960,12 +982,14 @@ static void page_faults_perf_counter_read(struct perf_counter *counter) 
	page_faults_perf_counter_update(counter);

}



static void page_faults_perf_counter_enable(struct perf_counter *counter)

static int page_faults_perf_counter_enable(struct perf_counter *counter)

{

	/*

	 * page-faults is a per-task value already,

	 * so we dont have to clear it on switch-in.

	 */



	return 0;

}



static void page_faults_perf_counter_disable(struct perf_counter *counter)
@@ -1006,12 +1030,14 @@ static void context_switches_perf_counter_read(struct perf_counter *counter) 
	context_switches_perf_counter_update(counter);

}



static void context_switches_perf_counter_enable(struct perf_counter *counter)

static int context_switches_perf_counter_enable(struct perf_counter *counter)

{

	/*

	 * ->nvcsw + curr->nivcsw is a per-task value already,

	 * so we dont have to clear it on switch-in.

	 */



	return 0;

}



static void context_switches_perf_counter_disable(struct perf_counter *counter)
@@ -1050,12 +1076,14 @@ static void cpu_migrations_perf_counter_read(struct perf_counter *counter) 
	cpu_migrations_perf_counter_update(counter);

}



static void cpu_migrations_perf_counter_enable(struct perf_counter *counter)

static int cpu_migrations_perf_counter_enable(struct perf_counter *counter)

{

	/*

	 * se.nr_migrations is a per-task value already,

	 * so we dont have to clear it on switch-in.

	 */



	return 0;

}



static void cpu_migrations_perf_counter_disable(struct perf_counter *counter)