[dpdk-dev] [PATCH v2 5/7] examples/l3fwd: add neon support for l3fwd

[Sekhar, Ashwin]

On Thu, 2017-05-11 at 04:14 +0000, Sekhar, Ashwin wrote:
...
> > > Combining all the above comments, I made some changes on top of
> > > your
> > > patch. These changes are giving 3-4% improvement over your
> > > version.
> > > 
> > > You may find the changes at
> > > https://gist.github.com/ashwinyes/34cbdd999784402c859c71613587faf
> > > c
> > > 
> > Is the correct in Line 103/104, you only process one packets in the
> > last FWDSTEP packets?
> Its doing processx4_* there. So its processing 4 packets.
> 
> > 
> > Actually, I don't like your change in l3fwd_lpm_send_packets,
> > making
> > the simple logic complicated. And I don't think it can help to
> > improve
> > performance. :-)
> Its not making it complicated. The number of lines of code may be
> higher by may be 10 lines, but the conditions of the loops are
> simplified which reduces the number of branch instructions and helps
> the processor to go through them faster.
> 
> If possible, please try it out on your machine.

Missed out one point.
Since 2 loops are form "for (i = 0; i < FWDSTEP; i++)" i.e. looping for
constant number of iterations, compiler will easily unroll them.

Thanks
Ashwin
> > 
> > 
> > > 
> > > 
> > > Please check it out and let me know your comments.
> > > 
> > > Thanks
> > > Ashwin