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.
