istio.io/content/help/faq/distributed-tracing/why-mixer-spans.md

title	weight
Why do I see 'istio-mixer' spans in some of my distributed traces?	100

Mixer generates application-level traces for requests that reach Mixer with tracing headers. Mixer generates spans, labeled 'istio-mixer' for any critical work that it does, including dispatch to individual adapters.

Envoy caches calls to Mixer on the data path. As a result, calls out to Mixer made via the istio-policy service only happen for certain requests, for example: cache-expiry or different request characteristics. For this reason, you only see Mixer participate in some of your traces.

To turn off the application-level trace spans for Mixer itself, you must edit the deployment configuration for istio-policy and remove the --trace_zipkin_url command-line parameter.