libmemif: example app can generate ICMP, dev perf tests (using icmpr-epoll)

Change-Id: Ib72ede51559754f606c0a1d57f4fb624d032caa6
Signed-off-by: Jakub Grajciar <Jakub.Grajciar@pantheon.tech>

extras/libmemif/docs/devperftest_doc.md

@@ -0,0 +1,94 @@
+## Development performance test    {#libmemif_devperftest_doc}
+
+Simle test cases using ICMP. icmpr-epoll example app generates and transmits packets over memif interface.
+
+#### TC1: LIB-VPP
+
+Start icmpr-epoll example app and VPP.
+
+VPP-side config:
+```
+DBGvpp# create memif id 0 master
+DBGvpp# set int state memif0/0 up
+DBGvpp# set int ip address memif0/0 192.168.1.1/24
+```
+icmpr-epoll:
+```
+conn 0 0 1
+```
+> Last argument specifies interrupt function to use. This function only respondes to ARP requests. This is important because, packet generation and transmitting is handled by a separate thread. Calling memif_tx_burst from multiple threads writing on same queue could transmit uninitialized buffers.
+Once connection is established, you can send ping from VPP to icmpr-epoll app to learn its mac address.
+```
+DBGvpp# ping 192.168.1.2
+```
+> There should be no ICMP response. Only ARP response.
+Now send ICMP requests from icmpr-epoll:
+```
+send <index> <num-of-packets> <ip_daddr> <hw_daddr>
+send 0 5 192.168.1.1 02:fe:ff:ff:ff:ff
+```
+this command will create new thread which will generate icmp packets and transmit them over memif connection with specified index. Once the sequence is finished status will be printed.
+
+###### Example results (owerview of test data)
+
+(This test was run with modofication in VPP-memif plugin. The modification disallows memif tx node to allocate last ring buffer)
+lib-tx: 200M (if ring full don't drop packets)
+vpp-rx: 200M
+vpp-tx: 200M - 50K (if ring full drop packets)
+lib-rx: =vpp-tx
+drop: ~0.025% (full ring)
+pps: ~650K
+multiple interfaces:
+pps: divided
+drop: constant
+
+#### TC2: LIB-LIB
+
+This test case will not drop packets if memif ring is full. Instead it will loop until all required packets have been sent.
+
+Start two instances of icmpr-epoll example app.
+instance 1:
+```
+conn 0 1 0
+```
+instance 2:
+```
+conn 0 0 1
+send 0 5 192.168.1.1 aa:aa:aa:aa:aa:aa
+```
+> icmpr-epoll example app doesn't check ip or mac address so as long as the format is correct you can type anything as ip_daddr and hw_daddr arguments.
+
+###### Example results (owerview of test data)
+
+lib1-tx: 200M (if ring full don't drop packets)
+lib2-rx: 200M
+lib2-tx: 200M (if ring full don't drop packets)
+lib1-rx: 200M
+drop: obsolete
+pps: 4.5M
+multiple interfaces:
+not tested (excpected same as TC1)
+
+#### TC3: LIB-LIB
+
+Start two instances of icmpr-epoll example app.
+instance 1:
+```
+conn 0 1
+```
+instance 2:
+```
+conn 0 0 1
+send 0 5 192.168.1.1 aa:aa:aa:aa:aa:aa
+```
+
+###### Example results (owerview of test data)
+
+lib1-tx: 200M (if ring full don't drop packets)
+lib2-rx: 200M
+lib2-tx: 169626182 (if ring full drop packets)
+lib1-rx: =lib2-tx
+drop: ~15%
+pps: ~6M
+multiple interfaces:
+not tested (excpected same as TC1)