Comparison
CPU throttlingvsResource limit
CPU throttling
average CPU use is twelve percent and the p99 latency is terrible, because the container is being stopped for milliseconds at a time.
The kernel pausing a container that has used its CPU quota within the current scheduling period. Because the quota is enforced per short window rather than on average, a workload that is bursty — which most request handlers are — gets throttled while looking idle in any per-minute graph. It is the most under-diagnosed source of tail latency on container platforms, and the metric for it is not CPU usage but throttled time.
Full entry →Resource limit
the container went one byte over its memory ceiling and the kernel killed it outright, mid-request.
The hard ceiling a container may consume, enforced by the kernel rather than by the scheduler. The two resources behave completely differently at the ceiling: CPU is throttled, so the workload gets slow, and memory is not compressible, so the process is killed. That asymmetry is why a CPU limit shows up as mysterious latency and a memory limit shows up as a restart loop.
Full entry →