[RFC PATCH 0/3] nvme sq associations

[Sagi Grimberg]

>> 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.