Restrict RSS Receive Queues

The ethtool -X command can also be used to restrict the receive queues accessible by RSS. In the following example rss_cpus=4 and ethtool -x identifies the four receive queues per interface:

# ethtool -x eth4

RX flow hash indirection table for eth4 with 4 RX ring(s):
    0:      0     1     2     3     0     1     2     3
    8:      0     1     2     3     0     1     2     3
   16:      0     1     2     3     0     1     2     3
   24:      0     1     2     3     0     1     2     3
   32:      0     1     2     3     0     1     2     3
   40:      0     1     2     3     0     1     2     3
   48:      0     1     2     3     0     1     2     3
   56:      0     1     2     3     0     1     2     3
   64:      0     1     2     3     0     1     2     3
   72:      0     1     2     3     0     1     2     3
   80:      0     1     2     3     0     1     2     3
   88:      0     1     2     3     0     1     2     3
   96:      0     1     2     3     0     1     2     3
  104:      0     1     2     3     0     1     2     3
  112:      0     1     2     3     0     1     2     3
  120:      0     1     2     3     0     1     2     3

To restrict RSS to spread receive flows evenly over the first two receive queues, use ethtool -X:

# ethtool -X eth4 equal 2

RX flow hash indirection table for eth4 with 4 RX ring(s):
    0:      0     1     0     1     0     1     0     1
    8:      0     1     0     1     0     1     0     1
   16:      0     1     0     1     0     1     0     1
   24:      0     1     0     1     0     1     0     1
   32:      0     1     0     1     0     1     0     1
   40:      0     1     0     1     0     1     0     1
   48:      0     1     0     1     0     1     0     1
   56:      0     1     0     1     0     1     0     1
   64:      0     1     0     1     0     1     0     1
   72:      0     1     0     1     0     1     0     1
   80:      0     1     0     1     0     1     0     1
   88:      0     1     0     1     0     1     0     1
   96:      0     1     0     1     0     1     0     1
  104:      0     1     0     1     0     1     0     1
  112:      0     1     0     1     0     1     0     1
  120:      0     1     0     1     0     1     0     1