Class: PerfCounters::Measurement

Inherits:
Object
  • Object
show all
Defined in:
lib/perf_counters.rb,
ext/perf_counters/perf_counters.c

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(events: [], exclude_kernel: true, disabled: true, exclude_hv: true) ⇒ Measurement

Returns a new instance of Measurement.



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# File 'lib/perf_counters.rb', line 53

def initialize(events: [], exclude_kernel: true, disabled: true, exclude_hv: true)
  @events = events

  @exclude_kernel = exclude_kernel
  @disabled = disabled
  @exclude_hv = exclude_hv

  @__events = @events.flat_map do |event|
    [event.name, event.type, event.value]
  end
end

Instance Attribute Details

#disabled ⇒ Object

Returns the value of attribute disabled.



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# File 'lib/perf_counters.rb', line 51

def disabled
  @disabled
end

#events ⇒ Object

Returns the value of attribute events.



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# File 'lib/perf_counters.rb', line 51

def events
  @events
end

#exclude_hv ⇒ Object

Returns the value of attribute exclude_hv.



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# File 'lib/perf_counters.rb', line 51

def exclude_hv
  @exclude_hv
end

#exclude_kernel ⇒ Object

Returns the value of attribute exclude_kernel.



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# File 'lib/perf_counters.rb', line 51

def exclude_kernel
  @exclude_kernel
end

Instance Method Details

#__start ⇒ Object 



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# File 'ext/perf_counters/perf_counters.c', line 52

VALUE
measurement_start(VALUE self) {
  VALUE rb_events = rb_iv_get(self, "@events");
  size_t rb_events_len = RARRAY_LEN(rb_events);

  struct perf_state *state;
  Data_Get_Struct(self, struct perf_state, state);
  state->started = 1;
  state->fds = xmalloc(sizeof(int) * rb_events_len);
  state->ids = xmalloc(sizeof(uint64_t) * rb_events_len);

  for (unsigned int i = 0; i < rb_events_len; i++) {
    VALUE rb__events = rb_iv_get(self, "@__events");
    // extract type, value
    VALUE type = rb_ary_entry(rb__events, (i * 3) + 1);
    VALUE config = rb_ary_entry(rb__events, (i * 3) + 2);

    memset(&pe, 0, sizeof(struct perf_event_attr));
    pe.type = NUM2INT(type);
    pe.config = NUM2INT(config);
    pe.size = sizeof(struct perf_event_attr);
    pe.disabled = rb_iv_get(self, "@disabled") == Qtrue ? 1 : 0;
    pe.exclude_kernel = rb_iv_get(self, "@exclude_kernel") == Qtrue ? 1 : 0;
    pe.exclude_hv = rb_iv_get(self, "@exclude_hv") == Qtrue ? 1 : 0;
    pe.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;

    int current_fd;
    if (i == 0) {
      current_fd = perf_event_open(&pe, 0, -1, -1, 0);
    } else {
      current_fd = perf_event_open(&pe, 0, -1, LEADER(state->fds), 0);
    }

    if (current_fd == -1) {
      state->started = 0;
      xfree(state->fds);
      xfree(state->ids);

      rb_raise(rb_eArgError, "perf_event_open failed type=%d, config=%d. Check "
                             "your Linux kernel's version source code to see "
                             "if this event exists in "
                             "'include/uapi/linux/perf_event.h'",
               NUM2INT(type), NUM2INT(config));
    }

    state->fds[i] = current_fd;
    RAISE_ON_ERROR(ioctl(current_fd, PERF_EVENT_IOC_ID, &state->ids[i]));
  }

  RAISE_ON_ERROR(
      ioctl(LEADER(state->fds), PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP));
  RAISE_ON_ERROR(
      ioctl(LEADER(state->fds), PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP));

  return Qtrue;
}

#__stop ⇒ Object 



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# File 'ext/perf_counters/perf_counters.c', line 109

VALUE
measurement_stop(VALUE self) {
  struct perf_state *state;
  Data_Get_Struct(self, struct perf_state, state);

  if (!state->started) {
    return Qnil;
  }

  VALUE rb_events = rb_iv_get(self, "@events");
  size_t rb_events_len = RARRAY_LEN(rb_events);
  // TODO: check the buffer size is ok
  size_t buffer_size =
      (sizeof(uint64_t) + (sizeof(uint64_t) * 2 * rb_events_len));
  char buffer[buffer_size];
  memset(buffer, 0, buffer_size);
  struct read_format *rf = (struct read_format *)buffer;

  RAISE_ON_ERROR(
      ioctl(LEADER(state->fds), PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP));
  ssize_t read_bytes = read(LEADER(state->fds), buffer, sizeof(buffer));

  for (unsigned int i = 0; i < rb_events_len; i++) {
    close(state->fds[i]);
  }
  xfree(state->fds);
  xfree(state->ids);

  if (read_bytes == -1) {
    rb_raise(rb_eArgError, "read of the performance counters failed");
    return Qnil;
  }

  VALUE rb_array_result = rb_ary_new();

  // Assuming here that the events are in the same order they are requested
  for (unsigned int i = 0; i < rb_events_len; i++) {
    rb_ary_push(rb_array_result, INT2NUM(rf->values[i].value));
  }

  state->started = 0;
  return rb_array_result;
}

#start ⇒ Object 



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# File 'lib/perf_counters.rb', line 65

def start
  __start
end

#stop ⇒ Object 



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# File 'lib/perf_counters.rb', line 69

def stop
  return nil unless result_array = __stop

  result_array.each_with_object({}).with_index do |(result, final), i|
    final[events[i].name] = result
  end
end