On 3/3/2026 4:00 PM, Bruce Richardson wrote:
Recent rework of the Tx single-queue path in idpf aligned that path with
that of other drivers, meaning it now supports segments of size greater
than 16k. Rework the split-queue path to similarly support those large
segments.
Fixes: 770f4dfe0f79 ("net/idpf: support basic Tx data path")
Cc: [email protected]
Signed-off-by: Bruce Richardson <[email protected]>
---
<snip>
uint64_t cd_qw0 = 0, cd_qw1 = 0;
nb_ctx = idpf_set_tso_ctx(ol_flags, tx_pkt, &tx_offload, txq,
&cd_qw0, &cd_qw1);
- /* Calculate the number of TX descriptors needed for
- * each packet. For TSO packets, use ci_calc_pkt_desc as
- * the mbuf data size might exceed max data size that hw allows
- * per tx desc.
+ /* Calculate the number of TX descriptors needed for each
packet.
+ * For TSO packets, use ci_calc_pkt_desc as the mbuf data size
+ * might exceed the max data size that hw allows per tx desc.
*/
- if (ol_flags & RTE_MBUF_F_TX_TCP_SEG)
+ if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG))
This looks like a drive-by fix for an unrelated issue. That particular
code was introduced here:
2904020f8313 ("net/intel: add common function to calculate needed descs")
There are other drivers that check TSO flags but only look at TCP_SEG
but not UDP_SEG - should they all look for both? Perhaps this should be
looked at and fixed across all our PMD's that support TSO.
(to be clear, this is a general question, I'm not implying these changes
must be part of this patchset)
nb_used = ci_calc_pkt_desc(tx_pkt) + nb_ctx;
else
nb_used = tx_pkt->nb_segs + nb_ctx;
+ if (txq->nb_tx_free <= txq->tx_free_thresh) {
+ /* TODO: Need to refine
+ * 1. free and clean: Better to decide a clean
destination instead of
+ * loop times. And don't free mbuf when RS got
immediately, free when
+ * transmit or according to the clean destination.
+ * Now, just ignore the RE write back, free mbuf when
get RS
+ * 2. out-of-order rewrite back haven't be supported,
SW head and HW head
+ * need to be separated.
+ **/
+ nb_to_clean = 2 * txq->tx_rs_thresh;
+ while (nb_to_clean--)
+ idpf_split_tx_free(txq->complq);
+ }
+
+ if (txq->nb_tx_free < nb_used)
+ break;
+
if (ol_flags & CI_TX_CKSUM_OFFLOAD_MASK)
cmd_dtype = IDPF_TXD_FLEX_FLOW_CMD_CS_EN;
@@ -959,30 +959,52 @@ idpf_dp_splitq_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
ctx_desc[0] = cd_qw0;
ctx_desc[1] = cd_qw1;
- tx_id++;
- if (tx_id == txq->nb_tx_desc)
+ if (++tx_id == txq->nb_tx_desc)
tx_id = 0;
}
+ cmd_dtype |= IDPF_TX_DESC_DTYPE_FLEX_FLOW_SCHE;
+ struct rte_mbuf *m_seg = tx_pkt;
do {
- txd = &txr[tx_id];
- txn = &sw_ring[txe->next_id];
- txe->mbuf = tx_pkt;
+ uint64_t buf_dma_addr = rte_mbuf_data_iova(m_seg);
+ uint16_t slen = m_seg->data_len;
+
+ txe->mbuf = m_seg;
CodeRabbit picked up on something here, and I think it's worth highlighting.
When we're splitting segments, we assign txe->mbuf to the first segment...
<snip>
+ txe = &sw_ring[sw_id];
+ /* sub-descriptor slots do not own the mbuf */
+ txe->mbuf = NULL;
...then set subsequent segments to NULL...
+ }
- /* Setup TX descriptor */
- txd->buf_addr =
- rte_cpu_to_le_64(rte_mbuf_data_iova(tx_pkt));
- cmd_dtype |= IDPF_TX_DESC_DTYPE_FLEX_FLOW_SCHE;
+ /* Write the final (or only) descriptor for this
segment */
+ txd = &txr[tx_id];
+ txd->buf_addr = rte_cpu_to_le_64(buf_dma_addr);
txd->qw1.cmd_dtype = cmd_dtype;
- txd->qw1.rxr_bufsize = tx_pkt->data_len;
+ txd->qw1.rxr_bufsize = slen;
txd->qw1.compl_tag = sw_id;
...and we're supposed to write the final descriptor here, but we've
stored the mbuf pointer in the *first* descriptor, not in the *last*
one, which means when this descriptor gets to processing completions,
the mbuf pointer of that descriptor will be NULL? Is that intended?
- tx_id++;
- if (tx_id == txq->nb_tx_desc)
+ if (++tx_id == txq->nb_tx_desc)
tx_id = 0;
sw_id = txe->next_id;
- txe = txn;
- tx_pkt = tx_pkt->next;
- } while (tx_pkt);
+ txe = &sw_ring[sw_id];
+ m_seg = m_seg->next;
+ } while (m_seg);
/* fill the last descriptor with End of Packet (EOP) bit */
txd->qw1.cmd_dtype |= IDPF_TXD_FLEX_FLOW_CMD_EOP;
--
Thanks,
Anatoly
