bpf: Investigate the *best* value for wakeup_data_size #1660
Description
What would you like to be added?
This constant:
https://github.com/sustainable-computing-io/kepler/blob/main/bpf/kepler.bpf.c#L70
Declares how often we wake up to read the ringbuf.
The current math was as follows:
- My system (on average) processes around 600-700 context switches per second
- The sample period in Kepler is once every 3 seconds
- We need to read at least one batch of ringbuf events within that 3 second interval
So 1000 should have me read every 1.7ish seconds 😄
Why is this needed?
When kepler wakes up to read events it consumes CPU. Right now that's showing us as being somewhere between 1-3% mean CPU usage over time.
We should consider whether there is a better formula we could use to compute this magic number of 1000.
It could relate to the sample rate.
e.g 500 * SampleRate and perhaps even the 500 could come from something better than an educated guess.