[dpdk-users] dpdk packet loss,delay, retransmission

Anupama Laxmi anupamalaxmi4 at gmail.com
Sun Jul 21 11:41:34 CEST 2019


I see delay in TCP packet transfer while transferring huge files using
SSH/SCP. The delay is not seen with file sizes up to 35 MB. Beyond 35 MB
there is delay due to TCP out of order /retransmission and packet loss. For
file size 762835531 earlier it took 8 seconds for scp transfer now it takes
~~ 4 mins after DPDK upgrade. I suspected Small RX and TX queue size on
NICs which are connected to DPDK is causing packet drops.

   1. Increased TX queue and RX queue size as follows.
   RTE_TEST_RX_DESC_DEFAULT 128 RTE_TEST_TX_DESC_DEFAULT 512

to

RTE_TEST_RX_DESC_DEFAULT 4096 RTE_TEST_TX_DESC_DEFAULT 4096

Saw little improvement. The time taken for scp reduced to 2mins and 30
seconds for file of size 762835531.

   1. Tried to rate limit the TX rate using: rte_eth_set_queue_rate_limit
   API

Not seeing much improvement.

Please suggest ways to configure the mbuf,queue size to optimize the
performance and reduce the delay and drop in packet transfer.


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