On 8/26/2021 7:16 AM, kerneljasonxing@xxxxxxxxx wrote:
> From: Jason Xing <xingwanli@xxxxxxxxxxxx>
>
> Originally, ixgbe driver doesn't allow the mounting of xdpdrv if the
> server is equipped with more than 64 cpus online. So it turns out that
> the loading of xdpdrv causes the "NOMEM" failure.
>
> Actually, we can adjust the algorithm and then make it work through
> mapping the current cpu to some xdp ring with the protect of @tx_lock.
Thank you very much for working on this!
you should put your sign off block here, and then end with a triple-dash
"---"
then have your vN: updates below that, so they will be dropped from
final git apply. It's ok to have more than one triple-dash.
>
> v4:
> - Update the wrong commit messages. (Jason)
>
> v3:
> - Change nr_cpu_ids to num_online_cpus() (Maciej)
> - Rename MAX_XDP_QUEUES to IXGBE_MAX_XDP_QS (Maciej)
> - Rename ixgbe_determine_xdp_cpu() to ixgbe_determine_xdp_q_idx() (Maciej)
> - Wrap ixgbe_xdp_ring_update_tail() with lock into one function (Maciej)
>
> v2:
> - Adjust cpu id in ixgbe_xdp_xmit(). (Jesper)
> - Add a fallback path. (Maciej)
> - Adjust other parts related to xdp ring.
>
> Fixes: 33fdc82f08 ("ixgbe: add support for XDP_TX action")
> Co-developed-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Shujin Li <lishujin@xxxxxxxxxxxx>
> Signed-off-by: Jason Xing <xingwanli@xxxxxxxxxxxx>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe.h | 15 ++++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c | 9 ++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 64 ++++++++++++++++------
> .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 1 +
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 9 +--
> 5 files changed, 73 insertions(+), 25 deletions(-)
...
> @@ -8539,21 +8539,32 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
> int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter,
> struct xdp_frame *xdpf)
> {
> - struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()];
> struct ixgbe_tx_buffer *tx_buffer;
> union ixgbe_adv_tx_desc *tx_desc;
> + struct ixgbe_ring *ring;
> u32 len, cmd_type;
> dma_addr_t dma;
> + int index, ret;
> u16 i;
>
> len = xdpf->len;
>
> - if (unlikely(!ixgbe_desc_unused(ring)))
> - return IXGBE_XDP_CONSUMED;
> + index = ixgbe_determine_xdp_q_idx(smp_processor_id());
> + ring = adapter->xdp_ring[index];
> +
> + if (static_branch_unlikely(&ixgbe_xdp_locking_key))
> + spin_lock(&ring->tx_lock);
> +
> + if (unlikely(!ixgbe_desc_unused(ring))) {
> + ret = IXGBE_XDP_CONSUMED;
> + goto out;
> + }
This static key stuff is tricky code, but I guess if it works, then it's
better than nothing.
As Maciej also commented, I'd like to see some before/after numbers for
some of the xdp sample programs to make sure this doesn't cause a huge
regression on the xdp transmit path. A small regression would be ok,
since this *is* adding overhead.
Jesse
