Re: NVME performance regression in Linux 5.x due to lack of block level IO queueing

[Chaitanya Kulkarni]

> Thanks for the info. I don't know of anything block or nvme specific that might
> explain an order of magnitude perf difference.
> 
> Could you try the same test without the filesytems? You mentioned using mdraid,
> so try '--filename=/dev/mdX'. If that also shows similiar performance
> difference, try using one of your nvme member drives directly, like
> '--filename=/dev/nvme1n1'. That should isolate which subsystem is contributing
> to the difference.
> 

With Keith's suggestions you can always take the perf numbers and
compare before and after mainly for nvme_queue_rq() and nvme_irq().

-ck