'Return compute node stats totals from all cells.'

def compute_node_stats(self, ctxt):

    responses = self.msg_runner.compute_node_stats(ctxt)
    totals = {}
    for response in responses:
        data = response.value_or_raise()
        for (key, val) in data.items():
            totals.setdefault(key, 0)
            totals[key] += val
    return totals
