Hi,
1.Can you send the output on the switch for the port priority counters?
2. Can you send the running config of the switch, to make sure PFC is enabled.
3. Which adapter is used?
4. can you send the output for this
RX=`cat /sys/module/mlx4_en/parameters/pfcrx`;printf "0x%x\n" $RX
and
TX=`cat /sys/module/mlx4_en/parameters/pfctx`;printf "0x%x\n" $TX