On Tue, 8 Jul 2025, Lombardo, Ed wrote:
Hi Ivan,
Yes, only the user space created rings.
Can you add more to your thoughts?
I was seeking to address the probable confusion here. If the application creates
a SC / MP ring for its own pipiline logic using API [1] and then invokes another
API [2] to create a common "mbuf mempool" to be used with Rx and Tx queues of
the network ports, then the observed appearance of "common_ring_mp_enqueue" is
likely attributed to the fact that API [2] creates a ring-based mempool
internally, and in MP / MC mode by default. And the latter ring is not the same
as the one created by the application logic. These are two independent rings.
BTW, does your application set RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE offload flag
when configuring Tx port/queue offloads on the network ports?
Thank you.
[1]
https://doc.dpdk.org/api-25.03/rte__ring_8h.html#a155cb48ef311eddae9b2e34808338b17
[2]
https://doc.dpdk.org/api-25.03/rte__mbuf_8h.html#a8f4abb0d54753d2fde515f35c1ba402a
[3]
https://doc.dpdk.org/api-25.03/rte__mempool_8h.html#a0b64d611bc140a4d2a0c94911580efd5
Ed
-----Original Message-----
From: Ivan Malov <ivan.ma...@arknetworks.am>
Sent: Tuesday, July 8, 2025 10:19 AM
To: Lombardo, Ed <ed.lomba...@netscout.com>
Cc: Stephen Hemminger <step...@networkplumber.org>; users <users@dpdk.org>
Subject: RE: dpdk Tx falling short
External Email: This message originated outside of NETSCOUT. Do not click links
or open attachments unless you recognize the sender and know the content is
safe.
Hi Ed,
On Tue, 8 Jul 2025, Lombardo, Ed wrote:
Hi Stephen,
When I replace rte_eth_tx_burst() with mbuf free bulk I do not see the tx ring
fill up. I think this is valuable information. Also, perf analysis of the tx
thread shows common_ring_mp_enqueue and rte_atomic32_cmpset, where I did not
expect to see if I created all the Tx rings as SP and SC (and the workers and
ack rings as well, essentially all the 16 rings).
Perf report snippet:
+ 57.25% DPDK_TX_1 test [.] common_ring_mp_enqueue
+ 25.51% DPDK_TX_1 test [.] rte_atomic32_cmpset
+ 9.13% DPDK_TX_1 test [.] i40e_xmit_pkts
+ 6.50% DPDK_TX_1 test [.] rte_pause
0.21% DPDK_TX_1 test [.] rte_mempool_ops_enqueue_bulk.isra.0
0.20% DPDK_TX_1 test [.] dpdk_tx_thread
The traffic load is constant 10 Gbps 84 bytes packets with no idles. The burst
size of 512 is a desired burst of mbufs, however the tx thread will transmit
what ever it can get from the Tx ring.
I think if resolving why the perf analysis shows ring is MP when it has been
created as SP / SC should resolve this issue.
The 'common_ring_mp_enqueue' is the enqueue method of mempool variant 'ring',
that is, based on RTE Ring internally. When you say that ring has been created
as SP / SC you seemingly refer to the regular RTE ring created by your
application logic, not the internal ring of the mempool. Am I missing something?
Thank you.
Thanks,
ed
-----Original Message-----
From: Stephen Hemminger <step...@networkplumber.org>
Sent: Tuesday, July 8, 2025 9:47 AM
To: Lombardo, Ed <ed.lomba...@netscout.com>
Cc: Ivan Malov <ivan.ma...@arknetworks.am>; users <users@dpdk.org>
Subject: Re: dpdk Tx falling short
External Email: This message originated outside of NETSCOUT. Do not click links
or open attachments unless you recognize the sender and know the content is
safe.
On Tue, 8 Jul 2025 04:10:05 +0000
"Lombardo, Ed" <ed.lomba...@netscout.com> wrote:
Hi Stephen,
I ensured that in every pipeline stage that enqueue or dequeues mbufs it uses
the burst version, perf showed the repercussions of doing one mbuf dequeue and
enqueue.
For the receive stage rte_eth_rx_burst() is used and Tx stage we use
rte_eth_tx_burst(). The burst size used in tx_thread for dequeue burst is 512
Mbufs.
You might try buffering like rte_eth_tx_buffer does.
Need to add an additional mechanism to ensure that buffer gets flushed when you
detect idle period.
