On Tue, Jun 20, 2017 at 12:19:01PM +0200, Gaëtan Rivet wrote:

On Tue, Jun 20, 2017 at 11:58:54AM +0200, Thomas Monjalon wrote:

quoted

20/06/2017 11:22, Bruce Richardson:

quoted

On Mon, Jun 19, 2017 at 11:12:53PM +0200, Thomas Monjalon wrote:

quoted

15/06/2017 14:05, De Lara Guarch, Pablo:

quoted

quoted

Add parameter to start forwarding sending first
a burst of packets, which is useful when testing
a loopback connection.

This was already implemented as an internal command,
but adding it as a parameter is interesting, as it
allows the user to test a loopback connection without
entering in the internal command line.

Signed-off-by: Pablo de Lara <redacted>
---

--- a/doc/guides/testpmd_app_ug/run_app.rst
+++ b/doc/guides/testpmd_app_ug/run_app.rst

@@ -188,6 +188,14 @@ The commandline options are:

     Start forwarding on initialization.

+*   ``--tx-first``
+
+    Start forwarding, after sending a burst of packets first.
+
+.. Note::
+
+   This flag should be only used in non-interactive mode.

I don't really understand the benefit of this option.
Why is it better than
	echo start tx_first | testpmd -i
?

The one big difference I see is normal vs abnormal termination. With the
echo command you suggest, the only way to terminate testpmd is to kill
it via signal. With the extra cmdline option, it will cleanly exit via
enter as with non-interactive mode right now. Not a huge difference, but
I think having the extra argument to enable tx-first is useful.

Side note, one can:

(trap 'echo quit' SIGUSR1; echo 'start'; while true; do sleep 1; done) |testpmd -i &

and issue a SIGUSR1 to the subshell to cleanly quit testpmd.
Or:

(trap 'echo show port stats all' SIGUSR1; \
 trap 'echo quit' SIGUSR2; \
 echo 'start'; \
 while true; do :; done) |\
testpmd -i &

It's a little contrived, but it does the job and is easy enough to put
in scripts.

Or we can just put in a --tx-first flag and save the user the pain of
doing multi-line bash commands. Usability is a constant complaint about
DPDK that we hear e.g. at userspace every year, so we need to stop
assuming everyone looking to play with DPDK is a shell power-user.

/Bruce