I’m running a machine with ~2mio requests per day on rust. response times are sub 1ms, cpu usage is below 10%. yet, I’m getting throttled according to Grafana. >100% throttle, pretty much constantly.
what does it mean? why does firecracker report 30% load while my memory is at 50% and CPU below 10%? why am I getting throttled?
Since 1 vCPU on a shared machine equals to 1/16 of a full CPU, any CPU usage above 6.25% (1/16) will trigger a throttle. You can read a bit more in this other post: Predictable Processor Performance.
Or in the documentation here: CPU Performance · Fly Docs
@rodolfo thank you for the answer. I had to read up on cpu limits. I guess this was a new change in the later half of this year. Fully honoring the 1/16 CPU limit that is.
Now it does seem that there is a bug in Grafana here. Because I’ve had my machine at 2x shared cpu before, and switched it to 1x after seeing how little it was used. Now my graph does not have a ‘baseline’ yellow line. I think that’s why I’ve missed this overstepping of the limit.
All of my apps have this problem except for my newest staging app because I’ve changed the machine size up or down at least once for all my apps. It seems that Grafana won’t update the limit correctly. Sometimes it’s shown too high, sometimes too low, sometimes not at all. Is this a known issue?
This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.
