c['metrics'] = dict(log_interval=10, periodic_interval=10)
c['metrics'] can be a dictionary that configures various aspects of the metrics subsystem. If c['metrics'] is None, then metrics collection, logging and reporting will be disabled.
log_interval determines how often metrics should be logged to twistd.log. It default to 60s. If set to 0 or None, then logging of metrics will be disabled. This value can be changed via a reconfig.
periodic_interval determines how often various non-event based metrics are collected, such as memory usage, uncollectable garbage, reactor delay. This defaults to 10s. If set to 0 or None, then periodic collection of this data is disabled. This value can also be changed via a reconifg.
Read more about metrics in the Metrics section of the documentation.