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Commit 621a01ea authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf counters: hw driver API 



Impact: restructure code, introduce hw_ops driver abstraction

Introduce this abstraction to handle counter details:

 struct hw_perf_counter_ops {
	void (*hw_perf_counter_enable)	(struct perf_counter *counter);
	void (*hw_perf_counter_disable)	(struct perf_counter *counter);
	void (*hw_perf_counter_read)	(struct perf_counter *counter);
 };

This will be useful to support assymetric hw details, and it will also
be useful to implement "software counters". (Counters that count kernel
managed sw events such as pagefaults, context-switches, wall-clock time
or task-local time.)

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ccff286d

arch/x86/kernel/cpu/perf_counter.c

+27 −10
Original line number Diff line number Diff line
@@ -56,7 +56,7 @@ const int max_intel_perfmon_events = ARRAY_SIZE(intel_perfmon_event_map); 
/*

 * Setup the hardware configuration for a given hw_event_type

 */

int hw_perf_counter_init(struct perf_counter *counter)

static int __hw_perf_counter_init(struct perf_counter *counter)

{

	struct perf_counter_hw_event *hw_event = &counter->hw_event;

	struct hw_perf_counter *hwc = &counter->hw;
@@ -135,7 +135,7 @@ u64 hw_perf_disable_all(void) 
EXPORT_SYMBOL_GPL(hw_perf_disable_all);



static inline void

__hw_perf_counter_disable(struct hw_perf_counter *hwc, unsigned int idx)

__x86_perf_counter_disable(struct hw_perf_counter *hwc, unsigned int idx)

{

	wrmsr(hwc->config_base + idx, hwc->config, 0);

}
@@ -149,13 +149,13 @@ static void __hw_perf_counter_set_period(struct hw_perf_counter *hwc, int idx) 
	wrmsr(hwc->counter_base + idx, hwc->next_count, 0);

}



static void __hw_perf_counter_enable(struct hw_perf_counter *hwc, int idx)

static void __x86_perf_counter_enable(struct hw_perf_counter *hwc, int idx)

{

	wrmsr(hwc->config_base + idx,

	      hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE, 0);

}



void hw_perf_counter_enable(struct perf_counter *counter)

static void x86_perf_counter_enable(struct perf_counter *counter)

{

	struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

	struct hw_perf_counter *hwc = &counter->hw;
@@ -170,12 +170,12 @@ void hw_perf_counter_enable(struct perf_counter *counter) 


	perf_counters_lapic_init(hwc->nmi);



	__hw_perf_counter_disable(hwc, idx);

	__x86_perf_counter_disable(hwc, idx);



	cpuc->counters[idx] = counter;



	__hw_perf_counter_set_period(hwc, idx);

	__hw_perf_counter_enable(hwc, idx);

	__x86_perf_counter_enable(hwc, idx);

}



#ifdef CONFIG_X86_64
@@ -282,20 +282,20 @@ void perf_counter_print_debug(void) 
	local_irq_enable();

}



void hw_perf_counter_disable(struct perf_counter *counter)

static void x86_perf_counter_disable(struct perf_counter *counter)

{

	struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

	struct hw_perf_counter *hwc = &counter->hw;

	unsigned int idx = hwc->idx;



	__hw_perf_counter_disable(hwc, idx);

	__x86_perf_counter_disable(hwc, idx);



	clear_bit(idx, cpuc->used);

	cpuc->counters[idx] = NULL;

	__hw_perf_save_counter(counter, hwc, idx);

}



void hw_perf_counter_read(struct perf_counter *counter)

static void x86_perf_counter_read(struct perf_counter *counter)

{

	struct hw_perf_counter *hwc = &counter->hw;

	unsigned long addr = hwc->counter_base + hwc->idx;
@@ -342,7 +342,7 @@ static void perf_save_and_restart(struct perf_counter *counter) 
	__hw_perf_counter_set_period(hwc, idx);



	if (pmc_ctrl & ARCH_PERFMON_EVENTSEL0_ENABLE)

		__hw_perf_counter_enable(hwc, idx);

		__x86_perf_counter_enable(hwc, idx);

}



static void
@@ -572,3 +572,20 @@ void __init init_hw_perf_counters(void) 


	perf_counters_initialized = true;

}



static struct hw_perf_counter_ops x86_perf_counter_ops = {

	.hw_perf_counter_enable		= x86_perf_counter_enable,

	.hw_perf_counter_disable	= x86_perf_counter_disable,

	.hw_perf_counter_read		= x86_perf_counter_read,

};



struct hw_perf_counter_ops *hw_perf_counter_init(struct perf_counter *counter)

{

	int err;



	err = __hw_perf_counter_init(counter);

	if (err)

		return NULL;



	return &x86_perf_counter_ops;

}

include/linux/perf_counter.h

+15 −0
Original line number Diff line number Diff line
@@ -113,6 +113,17 @@ struct perf_data { 
	u8				data[PERF_DATA_BUFLEN];

};



struct perf_counter;



/**

 * struct hw_perf_counter_ops - performance counter hw ops

 */

struct hw_perf_counter_ops {

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

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

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

};



/**

 * struct perf_counter - performance counter kernel representation:

 */
@@ -120,6 +131,7 @@ struct perf_counter { 
	struct list_head		list_entry;

	struct list_head		sibling_list;

	struct perf_counter		*group_leader;

	struct hw_perf_counter_ops	*hw_ops;



	int				active;

#if BITS_PER_LONG == 64
@@ -185,6 +197,9 @@ struct perf_cpu_context { 
extern int perf_max_counters;



#ifdef CONFIG_PERF_COUNTERS

extern struct hw_perf_counter_ops *

hw_perf_counter_init(struct perf_counter *counter);



extern void perf_counter_task_sched_in(struct task_struct *task, int cpu);

extern void perf_counter_task_sched_out(struct task_struct *task, int cpu);

extern void perf_counter_task_tick(struct task_struct *task, int cpu);

kernel/perf_counter.c

+24 −21
Original line number Diff line number Diff line
@@ -37,15 +37,12 @@ static DEFINE_MUTEX(perf_resource_mutex); 
/*

 * Architecture provided APIs - weak aliases:

 */



int __weak hw_perf_counter_init(struct perf_counter *counter)

extern __weak struct hw_perf_counter_ops *

hw_perf_counter_init(struct perf_counter *counter)

{

	return -EINVAL;

	return ERR_PTR(-EINVAL);

}



void __weak hw_perf_counter_enable(struct perf_counter *counter)	 { }

void __weak hw_perf_counter_disable(struct perf_counter *counter)	 { }

void __weak hw_perf_counter_read(struct perf_counter *counter)		 { }

void __weak hw_perf_disable_all(void)	 { }

void __weak hw_perf_enable_all(void)	 { }

void __weak hw_perf_counter_setup(void)	 { }
@@ -146,7 +143,7 @@ static void __perf_counter_remove_from_context(void *info) 
	spin_lock(&ctx->lock);



	if (counter->active) {

		hw_perf_counter_disable(counter);

		counter->hw_ops->hw_perf_counter_disable(counter);

		counter->active = 0;

		ctx->nr_active--;

		cpuctx->active_oncpu--;
@@ -257,7 +254,7 @@ static void __perf_install_in_context(void *info) 
	ctx->nr_counters++;



	if (cpuctx->active_oncpu < perf_max_counters) {

		hw_perf_counter_enable(counter);

		counter->hw_ops->hw_perf_counter_enable(counter);

		counter->active = 1;

		counter->oncpu = cpu;

		ctx->nr_active++;
@@ -333,7 +330,7 @@ counter_sched_out(struct perf_counter *counter, 
	if (!counter->active)

		return;



	hw_perf_counter_disable(counter);

	counter->hw_ops->hw_perf_counter_disable(counter);

	counter->active	=  0;

	counter->oncpu	= -1;
@@ -392,7 +389,7 @@ counter_sched_in(struct perf_counter *counter, 
		 struct perf_counter_context *ctx,

		 int cpu)

{

	hw_perf_counter_enable(counter);

	counter->hw_ops->hw_perf_counter_enable(counter);

	counter->active = 1;

	counter->oncpu = cpu;	/* TODO: put 'cpu' into cpuctx->cpu */
@@ -509,7 +506,9 @@ void perf_counter_init_task(struct task_struct *task) 
 */

static void __hw_perf_counter_read(void *info)

{

	hw_perf_counter_read(info);

	struct perf_counter *counter = info;



	counter->hw_ops->hw_perf_counter_read(counter);

}



static u64 perf_counter_read(struct perf_counter *counter)
@@ -816,8 +815,10 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, 
		   int cpu,

		   struct perf_counter *group_leader)

{

	struct perf_counter *counter = kzalloc(sizeof(*counter), GFP_KERNEL);

	struct hw_perf_counter_ops *hw_ops;

	struct perf_counter *counter;



	counter = kzalloc(sizeof(*counter), GFP_KERNEL);

	if (!counter)

		return NULL;
@@ -839,6 +840,14 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, 
	counter->hw_event		= *hw_event;

	counter->wakeup_pending		= 0;

	counter->group_leader		= group_leader;

	counter->hw_ops			= NULL;



	hw_ops = hw_perf_counter_init(counter);

	if (!hw_ops) {

		kfree(counter);

		return NULL;

	}

	counter->hw_ops = hw_ops;



	return counter;

}
@@ -908,10 +917,6 @@ asmlinkage int sys_perf_counter_open( 
	if (!counter)

		goto err_put_context;



	ret = hw_perf_counter_init(counter);

	if (ret)

		goto err_free_put_context;



	perf_install_in_context(ctx, counter, cpu);



	ret = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0);
@@ -927,8 +932,6 @@ asmlinkage int sys_perf_counter_open( 
	mutex_lock(&counter->mutex);

	perf_counter_remove_from_context(counter);

	mutex_unlock(&counter->mutex);



err_free_put_context:

	kfree(counter);



err_put_context: