Here in the Linux Plumbers Conference talk regarding the NVMe driver (the same one discussed in the OP), the benchmarks show nearly identical performance to the existing implementation. At the end of the talk the co-author of the NVMe spec (Matthew Wilcox) made a point to stand up and comment with how unexpectedly impressed he is with the performance: "I was not expecting to see these performance numbers, they are amazing." (at this timestamp: https://youtu.be/Xw9pKeJ-4Bw?t=9486 ).
Here in the Linux Plumbers Conference talk regarding the NVMe driver (the same one discussed in the OP), the benchmarks show nearly identical performance to the existing implementation. At the end of the talk the co-author of the NVMe spec (Matthew Wilcox) made a point to stand up and comment with how unexpectedly impressed he is with the performance: "I was not expecting to see these performance numbers, they are amazing." (at this timestamp: https://youtu.be/Xw9pKeJ-4Bw?t=9486 ).
EDIT: here's the timestamp of the benchmarks themselves: https://youtu.be/Xw9pKeJ-4Bw?t=8626