Monitoring is done in two parts: capacity and throughput.
Capacity is about the bots and what they are doing. Are bots efficient, mostly dead, or wasting their time either continuously rebooting or running bot_config hooks?
Throughput is about the tasks that are enqueued and executed. Are tasks pending for long, deduped at a good rate?
Swarming is designed to work with about 20k bots. To get data at a granularity of 1 minute, this means aggregating data of 33 bots per second on a continuous basis.
The way to achieve this is to precompute as much data in the current handlers, so that the computation handler collects the data, and fill the holes.
Swarming is designed to work at a rate of 20 tasks created per second. In practice task rate is much lower since the workload is either builds, which are generally at least in the order of several minutes, or test suites which also lasts several seconds, if not several minutes or hours.