The speed of reading DMA buf's data is too slow

[stone-sjj]

I find that when DMA rx data end, and I use send(fd, recv_buf, len, 0) to send data to net, the speed is too slow，why?

My platform is zynq-7000 and the interface is HP, do anyone konw how to solve the problem? Thanks!

[stone-sjj]

Now I guess this phenomenon is relevant to cache of DMA, but I don't konw how to solve it .

[ccasas777]

I have the same issue with zynq-7000. Do you know how to solve it?
It seems to be relevant to a cache issue as you said
What I did:

1. add dma-coherent: it led to some errors in the data.
2. try to use a zero-copy method moving dam buffer data directly used by the socket: I failed.
   However, even the idea succeed. The problem is still not solved, because Eventually, I need the data process in the user space before sending data out.