On Wed, 19 Aug 2020 15:13:48 +0200
Lorenzo Bianconi [off-list ref] wrote:
quoted
Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and
XDP remote drivers if this is a "non-linear" XDP buffer
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 832bbb8b05c8..36a3defa63fa 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2170,11 +2170,14 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
struct bpf_prog *prog, struct xdp_buff *xdp,
u32 frame_sz, struct mvneta_stats *stats)
{
+ struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
unsigned int len, data_len, sync;
u32 ret, act;
len = xdp->data_end - xdp->data_hard_start - pp->rx_offset_correction;
data_len = xdp->data_end - xdp->data;
+
+ xdp->mb = !!sinfo->nr_frags;
act = bpf_prog_run_xdp(prog, xdp);
Reading the memory sinfo->nr_frags could be a performance issue for our
baseline case of no-multi-buffer. As you are reading a cache-line that
you don't need to (and driver have not touch yet).
ack, I will rework it in v2 to remove this access.
Regards,
Lorenzo
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer