net: pktgen: packet bursting via skb->xmit_more

This patch demonstrates the effect of delaying update of HW tailptr.
(based on earlier patch by Jesper)

burst=1 is the default. It sends one packet with xmit_more=false
burst=2 sends one packet with xmit_more=true and
        2nd copy of the same packet with xmit_more=false
burst=3 sends two copies of the same packet with xmit_more=true and
        3rd copy with xmit_more=false

Performance with ixgbe (usec 30):
burst=1  tx:9.2 Mpps
burst=2  tx:13.5 Mpps
burst=3  tx:14.5 Mpps full 10G line rate

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/networking/pktgen.txt b/Documentation/networking/pktgen.txt
index 0dffc6e37902..6915c6b27869 100644
--- a/Documentation/networking/pktgen.txt
+++ b/Documentation/networking/pktgen.txt
@@ -99,6 +99,9 @@ Examples:
 
  pgset "clone_skb 1"     sets the number of copies of the same packet
  pgset "clone_skb 0"     use single SKB for all transmits
+ pgset "burst 8"         uses xmit_more API to queue 8 copies of the same
+                         packet and update HW tx queue tail pointer once.
+                         "burst 1" is the default
  pgset "pkt_size 9014"   sets packet size to 9014
  pgset "frags 5"         packet will consist of 5 fragments
  pgset "count 200000"    sets number of packets to send, set to zero