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net/mlx5: fix multi-segment inline for the first segments

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Before 19.08 release the Tx burst routines of mlx5 PMD
provided data inline for the first short segments of the
multi-segment packets. In the release 19.08 mlx5 Tx datapath
was refactored and this behavior was broken, affecting the
performance.

For example, the T-Rex traffic generator might use small
leading segments to handle packet headers and performance
degradation was noticed.

If the first segments of the multi-segment packet are short
and the overall length is below the inline threshold it
should be inline into the WQE to fix the performance.

Fixes: 18a1c20044 ("net/mlx5: implement Tx burst template")
Cc: stable@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
This commit is contained in:
Viacheslav Ovsiienko 2021-06-22 19:40:49 +03:00 committed by Raslan Darawsheh
parent 9f4a192328
commit ec837ad0fc
1 changed files with 13 additions and 15 deletions
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28
drivers/net/mlx5/mlx5_tx.h
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@ -2040,6 +2040,8 @@ mlx5_tx_packet_multi_inline(struct mlx5_txq_data *__rte_restrict txq,
unsigned int nxlen;
uintptr_t start;
mbuf = loc->mbuf;
nxlen = rte_pktmbuf_data_len(mbuf);
/*
* Packet length exceeds the allowed inline data length,
* check whether the minimal inlining is required.
@ -2049,28 +2051,23 @@ mlx5_tx_packet_multi_inline(struct mlx5_txq_data *__rte_restrict txq,
MLX5_ESEG_MIN_INLINE_SIZE);
MLX5_ASSERT(txq->inlen_mode <= txq->inlen_send);
inlen = txq->inlen_mode;
} else {
if (loc->mbuf->ol_flags & PKT_TX_DYNF_NOINLINE ||
!vlan || txq->vlan_en) {
/*
* VLAN insertion will be done inside by HW.
* It is not utmost effective - VLAN flag is
* checked twice, but we should proceed the
* inlining length correctly and take into
* account the VLAN header being inserted.
*/
return mlx5_tx_packet_multi_send
(txq, loc, olx);
}
} else if (vlan && !txq->vlan_en) {
/*
* VLAN insertion is requested and hardware does not
* support the offload, will do with software inline.
*/
inlen = MLX5_ESEG_MIN_INLINE_SIZE;
} else if (mbuf->ol_flags & PKT_TX_DYNF_NOINLINE ||
nxlen > txq->inlen_send) {
return mlx5_tx_packet_multi_send(txq, loc, olx);
} else {
goto do_first;
}
/*
* Now we know the minimal amount of data is requested
* to inline. Check whether we should inline the buffers
* from the chain beginning to eliminate some mbufs.
*/
mbuf = loc->mbuf;
nxlen = rte_pktmbuf_data_len(mbuf);
if (unlikely(nxlen <= txq->inlen_send)) {
/* We can inline first mbuf at least. */
if (nxlen < inlen) {
@ -2092,6 +2089,7 @@ mlx5_tx_packet_multi_inline(struct mlx5_txq_data *__rte_restrict txq,
goto do_align;
}
}
do_first:
do {
inlen = nxlen;
mbuf = NEXT(mbuf);