Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx> writes:
> This improves XDP_TX performance by about 8%.
>
> Here are single core XDP_TX test results. CPU consumptions are taken
> from "perf report --no-child".
>
> - Before:
>
> 7.26 Mpps
>
> _raw_spin_lock 7.83%
> veth_xdp_xmit 12.23%
>
> - After:
>
> 7.84 Mpps
>
> _raw_spin_lock 1.17%
> veth_xdp_xmit 6.45%
>
> Signed-off-by: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
> ---
> drivers/net/veth.c | 26 +++++++++++++++++++++++++-
> 1 file changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> index 52110e5..4edc75f 100644
> --- a/drivers/net/veth.c
> +++ b/drivers/net/veth.c
> @@ -442,6 +442,23 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
> return ret;
> }
>
> +static void veth_xdp_flush_bq(struct net_device *dev)
> +{
> + struct xdp_tx_bulk_queue *bq = this_cpu_ptr(&xdp_tx_bq);
> + int sent, i, err = 0;
> +
> + sent = veth_xdp_xmit(dev, bq->count, bq->q, 0);
Wait, veth_xdp_xmit() is just putting frames on a pointer ring. So
you're introducing an additional per-cpu bulk queue, only to avoid lock
contention around the existing pointer ring. But the pointer ring is
per-rq, so if you have lock contention, this means you must have
multiple CPUs servicing the same rq, no? So why not just fix that
instead?
-Toke
