Why are packet drops observed against 'rx_fifo_errors' parameter in the output of 'ethtool -S <interface>' ?

Issue

• The ethtool -S <interface> output shows receive fifo errors. Also reported are rx_queue_<n>_drops, the sum of which is equal to the rx_fifo_errors value.

  # ethtool -S eth0 | egrep 'rx_fifo|drops'
       rx_fifo_errors: 120674
       rx_queue_0_drops: 4032
       rx_queue_1_drops: 3036
       rx_queue_2_drops: 5904
       rx_queue_3_drops: 0
       rx_queue_4_drops: 228
       rx_queue_5_drops: 65656
       rx_queue_6_drops: 19267
       rx_queue_7_drops: 22551
  
  
  # ethtool -S eth0 | egrep drops | awk '{print $2}' | paste -s -d+ | bc
  120674