Re: [PATCH 1/7] perf: Add helper function to return number of counters

[Robert Richter <robert.richter@amd.com>]

On 04.10.10 16:44:19, Matt Fleming wrote:
> The number of counters for the registered pmu is needed in a few places
> so provide a helper function that returns this number.
> 
> Signed-off-by: Matt Fleming <matt@console-pimps.org>
> Tested-by: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm/kernel/perf_event.c |    6 ++++++
>  arch/arm/oprofile/common.c   |   31 ++++++++++++++++++-------------
>  arch/sh/kernel/perf_event.c  |    9 +++++++++
>  include/linux/perf_event.h   |    1 +
>  4 files changed, 34 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
> index ecbb028..ef3bc33 100644
> --- a/arch/arm/kernel/perf_event.c
> +++ b/arch/arm/kernel/perf_event.c
> @@ -123,6 +123,12 @@ armpmu_get_max_events(void)
>  }
>  EXPORT_SYMBOL_GPL(armpmu_get_max_events);
>  
> +int perf_num_counters(void)
> +{
> +	return armpmu_get_max_events();
> +}
> +EXPORT_SYMBOL_GPL(perf_num_counters);

Peter,

can you please ack this interface?

Thanks,

-Robert

> +
>  #define HW_OP_UNSUPPORTED		0xFFFF
>  
>  #define C(_x) \
> diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c
> index d660cb8..23f18a0 100644
> --- a/arch/arm/oprofile/common.c
> +++ b/arch/arm/oprofile/common.c
> @@ -43,7 +43,7 @@ static DEFINE_MUTEX(op_arm_mutex);
>  
>  static struct op_counter_config *counter_config;
>  static struct perf_event **perf_events[nr_cpumask_bits];
> -static int perf_num_counters;
> +static int perf_nr_counters;
>  
>  /*
>   * Overflow callback for oprofile.
> @@ -54,11 +54,11 @@ static void op_overflow_handler(struct perf_event *event, int unused,
>  	int id;
>  	u32 cpu = smp_processor_id();
>  
> -	for (id = 0; id < perf_num_counters; ++id)
> +	for (id = 0; id < perf_nr_counters; ++id)
>  		if (perf_events[cpu][id] == event)
>  			break;
>  
> -	if (id != perf_num_counters)
> +	if (id != perf_nr_counters)
>  		oprofile_add_sample(regs, id);
>  	else
>  		pr_warning("oprofile: ignoring spurious overflow "
> @@ -76,7 +76,7 @@ static void op_perf_setup(void)
>  	u32 size = sizeof(struct perf_event_attr);
>  	struct perf_event_attr *attr;
>  
> -	for (i = 0; i < perf_num_counters; ++i) {
> +	for (i = 0; i < perf_nr_counters; ++i) {
>  		attr = &counter_config[i].attr;
>  		memset(attr, 0, size);
>  		attr->type		= PERF_TYPE_RAW;
> @@ -131,7 +131,7 @@ static int op_perf_start(void)
>  	int cpu, event, ret = 0;
>  
>  	for_each_online_cpu(cpu) {
> -		for (event = 0; event < perf_num_counters; ++event) {
> +		for (event = 0; event < perf_nr_counters; ++event) {
>  			ret = op_create_counter(cpu, event);
>  			if (ret)
>  				goto out;
> @@ -150,7 +150,7 @@ static void op_perf_stop(void)
>  	int cpu, event;
>  
>  	for_each_online_cpu(cpu)
> -		for (event = 0; event < perf_num_counters; ++event)
> +		for (event = 0; event < perf_nr_counters; ++event)
>  			op_destroy_counter(cpu, event);
>  }
>  
> @@ -179,7 +179,7 @@ static int op_arm_create_files(struct super_block *sb, struct dentry *root)
>  {
>  	unsigned int i;
>  
> -	for (i = 0; i < perf_num_counters; i++) {
> +	for (i = 0; i < perf_nr_counters; i++) {
>  		struct dentry *dir;
>  		char buf[4];
>  
> @@ -353,14 +353,19 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
>  
>  	memset(&perf_events, 0, sizeof(perf_events));
>  
> -	perf_num_counters = armpmu_get_max_events();
> +	perf_nr_counters = perf_num_counters();
> +	if (perf_nr_counters <= 0) {
> +		pr_info("oprofile: no performance counters\n");
> +		ret = -ENODEV;
> +		goto out;
> +	}
>  
> -	counter_config = kcalloc(perf_num_counters,
> +	counter_config = kcalloc(perf_nr_counters,
>  			sizeof(struct op_counter_config), GFP_KERNEL);
>  
>  	if (!counter_config) {
>  		pr_info("oprofile: failed to allocate %d "
> -				"counters\n", perf_num_counters);
> +				"counters\n", perf_nr_counters);
>  		ret = -ENOMEM;
>  		goto out;
>  	}
> @@ -370,11 +375,11 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
>  		goto out;
>  
>  	for_each_possible_cpu(cpu) {
> -		perf_events[cpu] = kcalloc(perf_num_counters,
> +		perf_events[cpu] = kcalloc(perf_nr_counters,
>  				sizeof(struct perf_event *), GFP_KERNEL);
>  		if (!perf_events[cpu]) {
>  			pr_info("oprofile: failed to allocate %d perf events "
> -					"for cpu %d\n", perf_num_counters, cpu);
> +					"for cpu %d\n", perf_nr_counters, cpu);
>  			ret = -ENOMEM;
>  			goto out;
>  		}
> @@ -409,7 +414,7 @@ void __exit oprofile_arch_exit(void)
>  	struct perf_event *event;
>  
>  	for_each_possible_cpu(cpu) {
> -		for (id = 0; id < perf_num_counters; ++id) {
> +		for (id = 0; id < perf_nr_counters; ++id) {
>  			event = perf_events[cpu][id];
>  			if (event)
>  				perf_event_release_kernel(event);
> diff --git a/arch/sh/kernel/perf_event.c b/arch/sh/kernel/perf_event.c
> index 7a3dc35..2cb9ad5 100644
> --- a/arch/sh/kernel/perf_event.c
> +++ b/arch/sh/kernel/perf_event.c
> @@ -59,6 +59,15 @@ static inline int sh_pmu_initialized(void)
>  	return !!sh_pmu;
>  }
>  
> +int perf_num_counters(void)
> +{
> +	if (!sh_pmu)
> +		return 0;
> +
> +	return sh_pmu->num_events;
> +}
> +EXPORT_SYMBOL_GPL(perf_num_counters);
> +
>  /*
>   * Release the PMU if this is the last perf_event.
>   */
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 716f99b..1a02192 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -849,6 +849,7 @@ extern int perf_max_events;
>  
>  extern const struct pmu *hw_perf_event_init(struct perf_event *event);
>  
> +extern int perf_num_counters(void);
>  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);
> -- 
> 1.7.1
> 
> 

-- 
Advanced Micro Devices, Inc.
Operating System Research Center