[dpdk-dev] Flow control rx/tx mismatch?
Konieczny, TomaszX
tomaszx.konieczny at intel.com
Mon Sep 9 11:54:16 CEST 2019
Hi,
According to DPDK documentation:
"RX pause frame, enable flowctrl on TX side."
"TX pause frame, enable flowctrl on RX side".
While in testpmd (/app/test-pmd/cmdline.c):
/*
* Rx on/off, flow control is enabled/disabled on RX side. This can indicate
* the RTE_FC_TX_PAUSE, Transmit pause frame at the Rx side.
* Tx on/off, flow control is enabled/disabled on TX side. This can indicate
* the RTE_FC_RX_PAUSE, Respond to the pause frame at the Tx side.
*/
However the code looks like this:
static enum rte_eth_fc_mode rx_tx_onoff_2_lfc_mode[2][2] = {
{RTE_FC_NONE, RTE_FC_TX_PAUSE}, {RTE_FC_RX_PAUSE, RTE_FC_FULL}
fc_conf.mode = rx_tx_onoff_2_lfc_mode[rx_fc_en][tx_fc_en];
and
if ((fc_conf.mode == RTE_FC_RX_PAUSE) ||
(fc_conf.mode == RTE_FC_FULL))
rx_fc_en = 1;
if ((fc_conf.mode == RTE_FC_TX_PAUSE) ||
(fc_conf.mode == RTE_FC_FULL))
tx_fc_en = 1;
what suggest that rx_fc_en means RX_PAUSE not TX_PAUSE .
My personal tests also show, that RTE_FC_TX_PAUSE enables fc on transmission (responds to pause frame).
What is the actual desired action? Should rx_fc_en set RTE_FC_RX_PAUSE or RTE_FC_TX_PAUSE? In the first case, don't you think that the documentation entries are misleading? In later case, does DPDK work correctly and in line with documentation?
Regards
Tomasz Konieczny
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