Re: [dpdk-stable] [PATCH] app/testpmd: fix txonly flow generation entropy

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 2/9/2020 5:02 PM, Viacheslav Ovsiienko wrote:
> The testpmd application in txonly forwarding mode has an option
> to generate the packet flows by varying the destination IP address.
> The patch increments the IP for each packet sent, this improves
> the entropy and RSS distibution on the peer receiving size
> is getting more uniform.

The IP address already incremented for each packet sent [1], I can't see what
this patch adds.

[1]
http://lxr.dpdk.org/dpdk/v19.11/source/app/test-pmd/txonly.c#L208


btw, for reference the option mentioned is "--txonly-multi-flow" and it has been
added with:
commit: 82010ef55e7c ("app/testpmd: make txonly mode generate multiple flows")

> 
> Fixes: 82010ef55e7c ("app/testpmd: make txonly mode generate multiple flows")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
> ---
>  app/test-pmd/txonly.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/app/test-pmd/txonly.c b/app/test-pmd/txonly.c
> index 4b5bec4..8a1989f 100644
> --- a/app/test-pmd/txonly.c
> +++ b/app/test-pmd/txonly.c
> @@ -153,7 +153,6 @@
>  		const uint16_t vlan_tci_outer, const uint64_t ol_flags)
>  {
>  	struct rte_mbuf *pkt_segs[RTE_MAX_SEGS_PER_PKT];
> -	uint8_t  ip_var = RTE_PER_LCORE(_ip_var);
>  	struct rte_mbuf *pkt_seg;
>  	uint32_t nb_segs, pkt_len;
>  	uint8_t i;
> @@ -193,6 +192,7 @@
>  	copy_buf_to_pkt(&pkt_ip_hdr, sizeof(pkt_ip_hdr), pkt,
>  			sizeof(struct rte_ether_hdr));
>  	if (txonly_multi_flow) {
> +		uint8_t  ip_var = RTE_PER_LCORE(_ip_var);
>  		struct rte_ipv4_hdr *ip_hdr;
>  		uint32_t addr;
>  
> @@ -208,6 +208,7 @@
>  		 */
>  		addr = (tx_ip_dst_addr | (ip_var++ << 8)) + rte_lcore_id();
>  		ip_hdr->src_addr = rte_cpu_to_be_32(addr);
> +		RTE_PER_LCORE(_ip_var) = ip_var;
>  	}
>  	copy_buf_to_pkt(&pkt_udp_hdr, sizeof(pkt_udp_hdr), pkt,
>  			sizeof(struct rte_ether_hdr) +
> @@ -315,7 +316,7 @@
>  	fs->tx_packets += nb_tx;
>  
>  	if (txonly_multi_flow)
> -		RTE_PER_LCORE(_ip_var) += nb_tx;
> +		RTE_PER_LCORE(_ip_var) -= nb_pkt - nb_tx;
>  
>  #ifdef RTE_TEST_PMD_RECORD_BURST_STATS
>  	fs->tx_burst_stats.pkt_burst_spread[nb_tx]++;
>