Re: [PATCH net-next 09/16] idpf: remove SW marker handling from NAPI

Maciej Fijalkowski
2025-03-07T11:42:26Z

On Wed, Mar 05, 2025 at 05:21:25PM +0100, Alexander Lobakin wrote:
> From: Michal Kubiak <michal.kubiak@intel.com>
>
> SW marker descriptors on completion queues are used only when a queue
> is about to be destroyed. It's far from hotpath and handling it in the
> hotpath NAPI poll makes no sense.
> Instead, run a simple poller after a virtchnl message for destroying
> the queue is sent and wait for the replies. If replies for all of the
> queues are received, this means the synchronization is done correctly
> and we can go forth with stopping the link.
>
> Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> ---
> drivers/net/ethernet/intel/idpf/idpf.h | 7 +-
> drivers/net/ethernet/intel/idpf/idpf_txrx.h | 4 +-
> drivers/net/ethernet/intel/idpf/idpf_lib.c | 2 -
> drivers/net/ethernet/intel/idpf/idpf_txrx.c | 108 +++++++++++-------
> .../net/ethernet/intel/idpf/idpf_virtchnl.c | 34 ++----
> 5 files changed, 80 insertions(+), 75 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/idpf/idpf.h b/drivers/net/ethernet/intel/idpf/idpf.h
> index 66544faab710..6b51a5dcc1e0 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf.h
> +++ b/drivers/net/ethernet/intel/idpf/idpf.h
> @@ -36,6 +36,7 @@ struct idpf_vport_max_q;
> #define IDPF_NUM_CHUNKS_PER_MSG(struct_sz, chunk_sz) \
> ((IDPF_CTLQ_MAX_BUF_LEN - (struct_sz)) / (chunk_sz))
>
> +#define IDPF_WAIT_FOR_MARKER_TIMEO 500
> #define IDPF_MAX_WAIT 500
>
> /* available message levels */
> @@ -224,13 +225,10 @@ enum idpf_vport_reset_cause {
> /**
> * enum idpf_vport_flags - Vport flags
> * @IDPF_VPORT_DEL_QUEUES: To send delete queues message
> - * @IDPF_VPORT_SW_MARKER: Indicate TX pipe drain software marker packets
> - * processing is done
> * @IDPF_VPORT_FLAGS_NBITS: Must be last
> */
> enum idpf_vport_flags {
> IDPF_VPORT_DEL_QUEUES,
> - IDPF_VPORT_SW_MARKER,
> IDPF_VPORT_FLAGS_NBITS,
> };
>
> @@ -289,7 +287,6 @@ struct idpf_port_stats {
> * @tx_itr_profile: TX profiles for Dynamic Interrupt Moderation
> * @port_stats: per port csum, header split, and other offload stats
> * @link_up: True if link is up
> - * @sw_marker_wq: workqueue for marker packets
> */
> struct idpf_vport {
> u16 num_txq;
> @@ -332,8 +329,6 @@ struct idpf_vport {
> struct idpf_port_stats port_stats;
>
> bool link_up;
> -
> - wait_queue_head_t sw_marker_wq;
> };
>
> /**
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> index 9f938301b2c5..dd6cc3b5cdab 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
> @@ -286,7 +286,6 @@ struct idpf_ptype_state {
> * bit and Q_RFL_GEN is the SW bit.
> * @__IDPF_Q_FLOW_SCH_EN: Enable flow scheduling
> * @__IDPF_Q_SW_MARKER: Used to indicate TX queue marker completions
> - * @__IDPF_Q_POLL_MODE: Enable poll mode
> * @__IDPF_Q_CRC_EN: enable CRC offload in singleq mode
> * @__IDPF_Q_HSPLIT_EN: enable header split on Rx (splitq)
> * @__IDPF_Q_FLAGS_NBITS: Must be last
> @@ -296,7 +295,6 @@ enum idpf_queue_flags_t {
> __IDPF_Q_RFL_GEN_CHK,
> __IDPF_Q_FLOW_SCH_EN,
> __IDPF_Q_SW_MARKER,
> - __IDPF_Q_POLL_MODE,
> __IDPF_Q_CRC_EN,
> __IDPF_Q_HSPLIT_EN,
>
> @@ -1044,6 +1042,8 @@ bool idpf_rx_singleq_buf_hw_alloc_all(struct idpf_rx_queue *rxq,
> u16 cleaned_count);
> int idpf_tso(struct sk_buff *skb, struct idpf_tx_offload_params *off);
>
> +void idpf_wait_for_sw_marker_completion(struct idpf_tx_queue *txq);
> +
> static inline bool idpf_tx_maybe_stop_common(struct idpf_tx_queue *tx_q,
> u32 needed)
> {
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> index f3aea7bcdaa3..e17582d15e27 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> @@ -1501,8 +1501,6 @@ void idpf_init_task(struct work_struct *work)
> index = vport->idx;
> vport_config = adapter->vport_config[index];
>
> - init_waitqueue_head(&vport->sw_marker_wq);
> -
> spin_lock_init(&vport_config->mac_filter_list_lock);
>
> INIT_LIST_HEAD(&vport_config->user_config.mac_filter_list);
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> index a240ed115e3e..4e3de6031422 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> @@ -1626,32 +1626,6 @@ int idpf_vport_queues_alloc(struct idpf_vport *vport)
> return err;
> }
>
> -/**
> - * idpf_tx_handle_sw_marker - Handle queue marker packet
> - * @tx_q: tx queue to handle software marker
> - */
> -static void idpf_tx_handle_sw_marker(struct idpf_tx_queue *tx_q)
> -{
> - struct idpf_netdev_priv *priv = netdev_priv(tx_q->netdev);
> - struct idpf_vport *vport = priv->vport;
> - int i;
> -
> - idpf_queue_clear(SW_MARKER, tx_q);
> - /* Hardware must write marker packets to all queues associated with
> - * completion queues. So check if all queues received marker packets
> - */
> - for (i = 0; i < vport->num_txq; i++)
> - /* If we're still waiting on any other TXQ marker completions,
> - * just return now since we cannot wake up the marker_wq yet.
> - */
> - if (idpf_queue_has(SW_MARKER, vport->txqs[i]))
> - return;
> -
> - /* Drain complete */
> - set_bit(IDPF_VPORT_SW_MARKER, vport->flags);
> - wake_up(&vport->sw_marker_wq);
> -}
> -
> /**
> * idpf_tx_clean_stashed_bufs - clean bufs that were stored for
> * out of order completions
> @@ -2008,6 +1982,19 @@ idpf_tx_handle_rs_cmpl_fb(struct idpf_tx_queue *txq,
> idpf_tx_clean_stashed_bufs(txq, compl_tag, cleaned, budget);
> }
>
> +/**
> + * idpf_tx_update_complq_indexes - update completion queue indexes
> + * @complq: completion queue being updated
> + * @ntc: current "next to clean" index value
> + * @gen_flag: current "generation" flag value
> + */
> +static void idpf_tx_update_complq_indexes(struct idpf_compl_queue *complq,
> + int ntc, bool gen_flag)
> +{
> + complq->next_to_clean = ntc + complq->desc_count;
> + idpf_queue_assign(GEN_CHK, complq, gen_flag);
> +}
> +
> /**
> * idpf_tx_finalize_complq - Finalize completion queue cleaning
> * @complq: completion queue to finalize
> @@ -2059,8 +2046,7 @@ static void idpf_tx_finalize_complq(struct idpf_compl_queue *complq, int ntc,
> tx_q->cleaned_pkts = 0;
> }
>
> - complq->next_to_clean = ntc + complq->desc_count;
> - idpf_queue_assign(GEN_CHK, complq, gen_flag);
> + idpf_tx_update_complq_indexes(complq, ntc, gen_flag);
> }
>
> /**
> @@ -2115,9 +2101,6 @@ static bool idpf_tx_clean_complq(struct idpf_compl_queue *complq, int budget,
> &cleaned_stats,
> budget);
> break;
> - case IDPF_TXD_COMPLT_SW_MARKER:
> - idpf_tx_handle_sw_marker(tx_q);
> - break;
> case -ENODATA:
> goto exit_clean_complq;
> case -EINVAL:
> @@ -2159,6 +2142,59 @@ static bool idpf_tx_clean_complq(struct idpf_compl_queue *complq, int budget,
> return !!complq_budget;
> }
>
> +/**
> + * idpf_wait_for_sw_marker_completion - wait for SW marker of disabled Tx queue
> + * @txq: disabled Tx queue
> + */
> +void idpf_wait_for_sw_marker_completion(struct idpf_tx_queue *txq)
> +{
> + struct idpf_compl_queue *complq = txq->txq_grp->complq;
> + struct idpf_splitq_4b_tx_compl_desc *tx_desc;
> + s16 ntc = complq->next_to_clean;
> + unsigned long timeout;
> + bool flow, gen_flag;
> + u32 pos = ntc;
> +
> + if (!idpf_queue_has(SW_MARKER, txq))
> + return;
> +
> + flow = idpf_queue_has(FLOW_SCH_EN, complq);
> + gen_flag = idpf_queue_has(GEN_CHK, complq);
> +
> + timeout = jiffies + msecs_to_jiffies(IDPF_WAIT_FOR_MARKER_TIMEO);
> + tx_desc = flow ? &complq->comp[pos].common : &complq->comp_4b[pos];
> + ntc -= complq->desc_count;

could we stop this logic? it was introduced back in the days as comparison
against 0 for wrap case was faster, here as you said it doesn't have much
in common with hot path.

> +
> + do {
> + struct idpf_tx_queue *tx_q;
> + int ctype;
> +
> + ctype = idpf_parse_compl_desc(tx_desc, complq, &tx_q,
> + gen_flag);
> + if (ctype == IDPF_TXD_COMPLT_SW_MARKER) {
> + idpf_queue_clear(SW_MARKER, tx_q);
> + if (txq == tx_q)
> + break;
> + } else if (ctype == -ENODATA) {
> + usleep_range(500, 1000);
> + continue;
> + }
> +
> + pos++;
> + ntc++;
> + if (unlikely(!ntc)) {
> + ntc -= complq->desc_count;
> + pos = 0;
> + gen_flag = !gen_flag;
> + }
> +
> + tx_desc = flow ? &complq->comp[pos].common :
> + &complq->comp_4b[pos];
> + prefetch(tx_desc);
> + } while (time_before(jiffies, timeout));

what if timeout expires and you didn't find the marker desc? why do you
need timer? couldn't you scan the whole ring instead?

> +
> + idpf_tx_update_complq_indexes(complq, ntc, gen_flag);
> +}
> /**
> * idpf_tx_splitq_build_ctb - populate command tag and size for queue
> * based scheduling descriptors
> @@ -4130,15 +4166,7 @@ static int idpf_vport_splitq_napi_poll(struct napi_struct *napi, int budget)
> else
> idpf_vport_intr_set_wb_on_itr(q_vector);
>
> - /* Switch to poll mode in the tear-down path after sending disable
> - * queues virtchnl message, as the interrupts will be disabled after
> - * that
> - */
> - if (unlikely(q_vector->num_txq && idpf_queue_has(POLL_MODE,
> - q_vector->tx[0])))
> - return budget;
> - else
> - return work_done;
> + return work_done;
> }
>
> /**
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
> index 135af3cc243f..24495e4d6c78 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
> @@ -752,21 +752,17 @@ int idpf_recv_mb_msg(struct idpf_adapter *adapter)
> **/
> static int idpf_wait_for_marker_event(struct idpf_vport *vport)
> {
> - int event;
> - int i;
> -
> - for (i = 0; i < vport->num_txq; i++)
> - idpf_queue_set(SW_MARKER, vport->txqs[i]);
> + bool markers_rcvd = true;
>
> - event = wait_event_timeout(vport->sw_marker_wq,
> - test_and_clear_bit(IDPF_VPORT_SW_MARKER,
> - vport->flags),
> - msecs_to_jiffies(500));
> + for (u32 i = 0; i < vport->num_txq; i++) {
> + struct idpf_tx_queue *txq = vport->txqs[i];
>
> - for (i = 0; i < vport->num_txq; i++)
> - idpf_queue_clear(POLL_MODE, vport->txqs[i]);
> + idpf_queue_set(SW_MARKER, txq);
> + idpf_wait_for_sw_marker_completion(txq);
> + markers_rcvd &= !idpf_queue_has(SW_MARKER, txq);
> + }
>
> - if (event)
> + if (markers_rcvd)
> return 0;
>
> dev_warn(&vport->adapter->pdev->dev, "Failed to receive marker packets\n");
> @@ -1993,24 +1989,12 @@ int idpf_send_enable_queues_msg(struct idpf_vport *vport)
> */
> int idpf_send_disable_queues_msg(struct idpf_vport *vport)
> {
> - int err, i;
> + int err;
>
> err = idpf_send_ena_dis_queues_msg(vport, false);
> if (err)
> return err;
>
> - /* switch to poll mode as interrupts will be disabled after disable
> - * queues virtchnl message is sent
> - */
> - for (i = 0; i < vport->num_txq; i++)
> - idpf_queue_set(POLL_MODE, vport->txqs[i]);
> -
> - /* schedule the napi to receive all the marker packets */
> - local_bh_disable();
> - for (i = 0; i < vport->num_q_vectors; i++)
> - napi_schedule(&vport->q_vectors[i].napi);
> - local_bh_enable();
> -
> return idpf_wait_for_marker_event(vport);
> }
>
> --
> 2.48.1
>