Re: [PATCH v6 04/10] libperf: Add evsel mmap support

[Jiri Olsa]

On Wed, Mar 10, 2021 at 05:08:31PM -0700, Rob Herring wrote:

SNIP

> +
>  static int
>  sys_perf_event_open(struct perf_event_attr *attr,
>  		    pid_t pid, int cpu, int group_fd,
> @@ -137,6 +147,8 @@ void perf_evsel__free_fd(struct perf_evsel *evsel)
>  {
>  	xyarray__delete(evsel->fd);
>  	evsel->fd = NULL;
> +	xyarray__delete(evsel->mmap);
> +	evsel->mmap = NULL;
>  }
>  
>  void perf_evsel__close(struct perf_evsel *evsel)
> @@ -156,6 +168,45 @@ void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu)
>  	perf_evsel__close_fd_cpu(evsel, cpu);
>  }
>  
> +int perf_evsel__mmap(struct perf_evsel *evsel, int pages)
> +{
> +	int ret, cpu, thread;
> +	struct perf_mmap_param mp = {
> +		.prot = PROT_READ | PROT_WRITE,
> +		.mask = (pages * page_size) - 1,
> +	};

I don't mind using evsel->fd for dimensions below,
but we need to check in here that it's defined,
that perf_evsel__open was called

jirka

> +
> +	if (evsel->mmap == NULL &&
> +	    perf_evsel__alloc_mmap(evsel, xyarray__max_x(evsel->fd), xyarray__max_y(evsel->fd)) < 0)
> +		return -ENOMEM;
> +
> +	for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
> +		for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
> +			int fd = FD(evsel, cpu, thread);
> +			struct perf_mmap *map = MMAP(evsel, cpu, thread);
> +
> +			if (fd < 0)
> +				continue;
> +
> +			perf_mmap__init(map, NULL, false, NULL);
> +
> +			ret = perf_mmap__mmap(map, &mp, fd, cpu);
> +			if (ret)
> +				return -1;
> +		}
> +	}
> +
> +	return 0;
> +}
> +

SNIP