quoted

The NVMe specification allows for namespaces with different performance
characteristics, as well as allowing IOs submissions to any namespace via
any non-empty submission queue. However, sharing queue resources between
namespaces with different performance characteristics can cause undesired
behavior (e.g. head-of-line-blocking for IOs that target a high-performance
namespace behind IOs that target a low performance namespace via the same
queue). In addition, the lack of hardware queue isolation support can cause
“noisy neighbor” type problems for applications issuing IOs to different
namespaces of the same controller. This problem may be especially pronounced
in multi-tenant environments such as the ones provided by cloud services.

For RFC such as this you need to provide a quantitative data for
different usecases for targeted (e.g. noisy neighbor problem) and non
targeted workloads (e.g. standard fio perf) and also the performance
impact of this change on the the hot path.

Agreed.

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