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

Jiri Olsa
2021-03-12T14:01:28Z

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