Re: [PATCH 2/6] testpmd: configurable tx_first burst number

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-05-26 02:53, Wang, Zhihong:
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > 2016-05-05 18:46, Zhihong Wang:
> > > This patch enables configurable tx_first burst number.
> > >
> > > Use "start tx_first (burst_num)" to specify how many bursts of packets to
> > > be sent before forwarding start, or "start tx_first" like before for the
> > > default 1 burst send.
> > 
> > The idea here is to fill the loopback latency gap with bursts.
> > Would it be possible to make it automatic by detecting the first
> > received packets to stop Tx generator?
> 
> The idea is great! The implementation might not be graceful though
> -- current tx_first mode first calls txonly engine before calling the
> actual engine, say iofwd, so iofwd is not established before tx_first
> is done, therefore no detection.

And what about rewriting tx_first?
No strong opinion. I let you and Pablo decide.

> It's possible to do this, but we need to implement another forward
> engine like "io_retry_fill_first" alone, it complicates testpmd just for
> this loop back test.
> 
> Looks to me it's better to use combination of existing fwd engines to
> do this, it's also more flexible with burst number parameters.