From: Christoph Paasch <cpaasch@xxxxxxxxxx>
mlx5e_skb_from_cqe_mpwrq_nonlinear() copies MLX5E_RX_MAX_HEAD (256)
bytes from the page-pool to the skb's linear part. Those 256 bytes
include part of the payload.
When attempting to do GRO in skb_gro_receive, if headlen > data_offset
(and skb->head_frag is not set), we end up aggregating packets in the
frag_list.
This is of course not good when we are CPU-limited. Also causes a worse
skb->len/truesize ratio,...
So, let's avoid copying parts of the payload to the linear part. We use
eth_get_headlen() to parse the headers and compute the length of the
protocol headers, which will be used to copy the relevant bits ot the
skb's linear part.
We still allocate MLX5E_RX_MAX_HEAD for the skb so that if the networking
stack needs to call pskb_may_pull() later on, we don't need to reallocate
memory.
This gives a nice throughput increase (ARM Neoverse-V2 with CX-7 NIC and
LRO enabled):
BEFORE:
=======
(netserver pinned to core receiving interrupts)
$ netperf -H 10.221.81.118 -T 80,9 -P 0 -l 60 -- -m 256K -M 256K
87380 16384 262144 60.01 32547.82
(netserver pinned to adjacent core receiving interrupts)
$ netperf -H 10.221.81.118 -T 80,10 -P 0 -l 60 -- -m 256K -M 256K
87380 16384 262144 60.00 52531.67
AFTER:
======
(netserver pinned to core receiving interrupts)
$ netperf -H 10.221.81.118 -T 80,9 -P 0 -l 60 -- -m 256K -M 256K
87380 16384 262144 60.00 52896.06
(netserver pinned to adjacent core receiving interrupts)
$ netperf -H 10.221.81.118 -T 80,10 -P 0 -l 60 -- -m 256K -M 256K
87380 16384 262144 60.00 85094.90
Additional tests across a larger range of parameters w/ and w/o LRO, w/
and w/o IPv6-encapsulation, different MTUs (1500, 4096, 9000), different
TCP read/write-sizes as well as UDP benchmarks, all have shown equal or
better performance with this patch.
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Saeed Mahameed <saeedm@xxxxxxxxxx>
Signed-off-by: Christoph Paasch <cpaasch@xxxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 8bedbda522808cbabc8e62ae91a8c25d66725ebb..0ac31c7fb64cd60720d390de45a5b6b453ed0a3f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -2047,6 +2047,8 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
dma_sync_single_for_cpu(rq->pdev, addr + head_offset, headlen,
rq->buff.map_dir);
+ headlen = eth_get_headlen(rq->netdev, head_addr, headlen);
+
frag_offset += headlen;
byte_cnt -= headlen;
linear_hr = skb_headroom(skb);
@@ -2123,6 +2125,9 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
pagep->frags++;
while (++pagep < frag_page);
}
+
+ headlen = eth_get_headlen(rq->netdev, mxbuf->xdp.data, headlen);
+
__pskb_pull_tail(skb, headlen);
} else {
if (xdp_buff_has_frags(&mxbuf->xdp)) {
--
2.50.1
