HORSE: Ultra-low latency workloads on FaaS platforms

We investigate if FaaS platforms can handle ultra-low latency workloads that run as low as less than 1μs and show that even for a warm start, the initialization time takes up to 99, 99% of the total execution time. This is due to the resume process of warm sandboxes that takes more time as the number of the sandbox's allocated virtual CPUs (vCPUs) increases. We uncover that two operations use up to 93, 1% of the resume time. The first is the insertion of the paused sandbox's vCPUs to a CPU-sorted run queue. The second is the update of a lock-protected variable, which represents the vCPUs' load on each CPU. This variable is used for frequency scaling.