Re: [PATCH v3 net-next] liquidio: improve UDP TX performance

From: Felix Manlunas <redacted>
Date: Mon, 6 Mar 2017 18:45:59 -0800

Improve UDP TX performance by:
* reducing the ring size from 2K to 512
* replacing the numerous streaming DMA allocations for info buffers and
  gather lists with one large consistent DMA allocation per ring

I applied this, because one should always use consistent mappings for
descriptor arrays and things like this, however I am confused about
this:

Also, finding an empty entry (in rbtree of device domain's iova mapping in
kernel) during Tx path becomes a bottleneck every so often; the loop to
find the empty entry goes through over 40K iterations;

A properly balanced tree should not require 40K iterations for a search.