Maybe a little bit later. But I think there is one slide is very good: http://pages.cs.wisc.edu/~danav/pubs/qcom/hexagon_hotchips2013.pdf
And Hexagon DSP has good support for fixed-int computation, but not be suitable for float arithmetic. Like hexagon has some instructions can be very useful for convolution, for example vrmpy, which could be used for dot.
And according to my test, SNPE on 8155 Hexagon could execute mobilenet v2 quant model in less than 5ms.
One more thing, thanks for the help and discussion of @kparzysz, based on his contributed runtime pr, I have completed TVM support of hexagon (LLVM hexagon CodeGen, schedule, hexagon parallel support and so on), but I must admit that we have big gap compared with SNPE, I am working on it. When time is suitable and follow up @kparzysz, I could contribute back to upstream.