When using cpu with hyper-threading, whether disable hyper-threading is a alway right policy?

[bithaifeng]

In the paper "haracterizing Microservice Dependency and Performance: Alibaba Trace Analysis" from SoCC'2021, Figure 14 shows that "When the host CPU utilization exceeds 40% (80%), the RT of a microservice can be degraded by more than 20% (30%) in average." Does it mean hyber-threading generate interference on others?

If someone want to use Microservice in a SMT CPU, another virtual core must stay free for QoS?