On Tue, May 14, 2013 at 07:13:53PM +0900, Namhyung Kim wrote:
> From: Namhyung Kim <[email protected]>
>
> The ftrace record command is for saving raw ftrace buffer contents
> which can be get from per_cpu/cpuX/trace_pipe_raw.
>
> Since ftrace events are generated very frequently so single thread for
> recording mostly resulted in buffer overruns. Thus it uses per-cpu
> recorder thread to prevent such cases and they save the contents to
> their own files.
>
SNIP
> +
> + /* synthesize sample data */
> + list_for_each_entry(fra, &recorders, node) {
> + struct perf_evsel *evsel = perf_evlist__first(ftrace->evlist);
> + union perf_event event = {
> + .sample = {
> + .header = {
> + .type = PERF_RECORD_SAMPLE,
> + .misc = PERF_RECORD_MISC_KERNEL,
> + .size = sizeof(event.sample.header) +
> + evsel->sample_size,
> + },
> + },
> + };
> + struct perf_sample sample = {
> + .cpu = fra->cpu,
> + .period = 1,
> + };
> + void *raw_data;
> + u32 raw_size;
> + int orig_size;
> +
> + if (fra->state != RECORD_STATE__DONE) {
> + pr_warning("recorder failed for some reason on cpu%d\n",
> + fra->cpu);
> + continue;
> + }
> +
> + perf_event__synthesize_sample(&event, evsel->attr.sample_type,
> + &sample, false);
> +
> + raw_data = synthesize_raw_data(evsel);
> + if (raw_data == NULL) {
> + pr_err("synthesizing raw sample failed\n");
> + goto out_fra;
> + }
> +
> + /*
> + * start of raw data is the size of raw data excluding itself.
> + */
> + raw_size = sizeof(u32) + (*(u32 *) raw_data);
> +
> + orig_size = event.sample.header.size;
> + event.sample.header.size += raw_size;
> +
> + err = write(perf_fd, &event.sample, orig_size);
> + if (err != orig_size) {
> + pr_err("write error occurred\n");
> + goto out_fra;
> + }
> +
> + err = write(perf_fd, raw_data, raw_size);
> + if (err != (int)raw_size) {
> + pr_err("write error occurred\n");
> + goto out_fra;
> + }
missing free(raw_data) ?
jirka
> +
> + session->header.data_size += event.sample.header.size;
> + }
> +
> + perf_session__write_header(session, ftrace->evlist, perf_fd, true);
> +
> +out_fra:
> + list_for_each_entry_safe(fra, tmp, &recorders, node) {
> + list_del(&fra->node);
> + free(fra);
> + }
> +out_session:
> + free(session);
> +out_close:
> + close(perf_fd);
> +out_reset:
> + reset_tracing_files(ftrace);
> return done ? 0 : -1;
> }
>
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