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SubjectRe: [PATCH 3/4] perf: teach perf inject to merge sched_stat_* and sched_switch events (v2)
On Tue, Aug 07, 2012 at 04:56:04PM +0400, Andrew Vagin wrote:
> +struct event_entry {
> + struct list_head node;
> + u32 pid;
> + union perf_event event[0];
> +};
> +
> +static LIST_HEAD(samples);
> +
> +static int perf_event__sched_stat(struct perf_tool *tool,
> + union perf_event *event,
> + struct perf_sample *sample,
> + struct perf_evsel *evsel,
> + struct machine *machine)
> +{
> + const char *evname = NULL;
> + uint32_t size;
> + struct event_entry *ent;
> + union perf_event *event_sw = NULL;
> + struct perf_sample sample_sw;
> + int sched_process_exit;
> +
> + size = event->header.size;
> +
> + evname = evsel->tp_format->name;
> +
> + sched_process_exit = !strcmp(evname, "sched_process_exit");
> +
> + if (!strcmp(evname, "sched_switch") || sched_process_exit) {
> + list_for_each_entry(ent, &samples, node)
> + if (sample->pid == ent->pid)

I suspect what you're rather interested in is the sample tid.

> + break;
> +
> + if (&ent->node != &samples) {
> + list_del(&ent->node);
> + free(ent);
> + }
> +
> + if (sched_process_exit)
> + return 0;
> +
> + ent = malloc(size + sizeof(struct event_entry));
> + if (ent == NULL)
> + die("malloc");
> + ent->pid = sample->pid;

Ditto.

> + memcpy(&ent->event, event, size);
> + list_add(&ent->node, &samples);
> + return 0;
> +
> + } else if (!strncmp(evname, "sched_stat_", 11)) {
> + u32 pid;
> +
> + pid = raw_field_value(evsel->tp_format,
> + "pid", sample->raw_data);

There you parse the pid from the trace content. That's fine because
it's actually the tid that is saved on the trace event. But this one
is not pid-namespace safe (it saves current->pid directly) while
sample->tid is pid-namespace safe (it uses task_pid_nr_ns).

So I suggest you to use sample->tid instead, plus that's going to be
consistant with what you did above.

Thanks.


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