net: atlantic: implement UDP GSO offload

atlantic hardware does support UDP hardware segmentation offload.
This allows user to specify one large contiguous buffer with data
which then will be split automagically into multiple UDP packets
of specified size.

Bulk sending of large UDP streams lowers CPU usage and increases
bandwidth.

We did estimations both with udpgso_bench_tx test tool and with modified
iperf3 measurement tool (4 streams, multithread, 200b packet size)
over AQC<->AQC 10G link. Flow control is disabled to prevent RX side
impact on measurements.

No UDP GSO:
	iperf3 -c 10.0.1.2 -u -b0 -l 200 -P4 --multithread
UDP GSO:
	iperf3 -c 10.0.1.2 -u -b0 -l 12600 --udp-lso 200 -P4 --multithread

Mode          CPU   iperf speed    Line speed   Packets per second
-------------------------------------------------------------
NO UDP GSO    350%   3.07 Gbps      3.8 Gbps     1,919,419
SW UDP GSO    200%   5.55 Gbps      6.4 Gbps     3,286,144
HW UDP GSO    90%    6.80 Gbps      8.4 Gbps     4,273,117

Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.h b/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
index be3702a4dcc9..991e4d31b094 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.h
@@ -65,19 +65,20 @@ struct __packed aq_ring_buff_s {
 	};
 	union {
 		struct {
-			u16 len;
+			u32 len:16;
 			u32 is_ip_cso:1;
 			u32 is_udp_cso:1;
 			u32 is_tcp_cso:1;
 			u32 is_cso_err:1;
 			u32 is_sop:1;
 			u32 is_eop:1;
-			u32 is_gso:1;
+			u32 is_gso_tcp:1;
+			u32 is_gso_udp:1;
 			u32 is_mapped:1;
 			u32 is_cleaned:1;
 			u32 is_error:1;
 			u32 is_vlan:1;
-			u32 rsvd3:5;
+			u32 rsvd3:4;
 			u16 eop_index;
 			u16 rsvd4;
 		};