EXIST: Enabling Extremely Efficient Intra-Service Tracing Observability in Datacenters

The complexity of online applications is rapidly increasing, bringing more sophisticated performance anomalies in today's cloud datacenter. To fully understand application behaviors, we should obtain both inter-service communication data via RPC-level tracing and intra-service execution traces via application-level tracing to precisely reason about event causality. However, the average time overhead of existing intra-service tracing schemes on the traced applications is generally about 5-10%, possibly reaching 18% in the worst case. To realize practical intra-service tracing in shared and stressed datacenters, one must achieve extreme tracing efficiency with an overhead at the per-mille level.

In this work, we present EXIST, an extremely efficient intra-service tracing system based on off-the-shelf hardware tracing capabilities. EXIST consists of three cooperative modules to pursue optimal trade-offs towards extremely low overhead. Firstly, it identifies and eliminates costly tracing control operations to guarantee the performance of the observed applications. Secondly, it allocates limited trace buffer space dynamically based on application status. Thirdly, it