The reason I wrote this script was because someone requested that I write it for them so that they can run it through all of our servers and see what the settings are set to....

A brief explanation of what RX Descriptors are.... 

Rx Descriptors is the Number of receive descriptors. A receive descriptor is a data structure that describes a receive buffer and its attributes to the network controller. The data in the descriptor is used by the controller to write data from the controller to host memory.

Example below from ethtool

# ethtool -g eth0
Ring parameters for eth0:
Pre-set maximums:
RX: 511
RX Mini: 0
RX Jumbo: 255
TX: 0
Current hardware settings:
RX: 511
RX Mini: 0
RX Jumbo: 100
TX: 511

Output of script below... run as root

python nic_rx_check.py
[FAIL] Current RX value = 128 (Required RX value = 16384)

#!/usr/bin/env python
#Create by Allen Sanabria
#To verify that the current RX Descriptors are set to the MAX of what it can handle.
#To set this value all you have to do is "ethtool -G <device> <MAX>"  ethtool -G eth0 511

#This script will reorder your vmnics for you
#Copyright (C) 2008 Allen Sanabria

#This program is free software; you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation; either version 2 of the License, or
#(at your option) any later version.

#This program is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
#GNU General Public License for more details.

#You should have received a copy of the GNU General Public License along
#with this program; if not, write to the Free Software Foundation, Inc.,
#51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import os, re

eth = []
cur_rx = {}
max_rx = {}
devices = open('/proc/net/dev', 'r').readlines()

root = 0
uid = os.getuid()
login = os.getlogin()

if uid == root:
  for lines in devices:
    match1 = re.search("(eth[0-9]+)\:", lines)
    if match1:
      eth.append(match1.group(1))
    else:
      continue

  for iface in eth:
    ethtool = 'ethtool -g %s' % (iface)
    ethtool_exec = os.popen(ethtool).readlines()
    for line in range(len(ethtool_exec)):
      match_max = re.search("^Pre-set\s+maximums\:", ethtool_exec[line])
      match_cur = re.search("^Current\s+hardware\s+settings\:", ethtool_exec[line])
      if match_max:
        match_value = re.search("(\d+)", ethtool_exec[line+1])
        max_rx[iface] = match_value.group(1)
      elif match_cur:
        match_value = re.search("(\d+)", ethtool_exec[line+1])
        cur_rx[iface] = match_value.group(1)
      else:
        continue
  for key in cur_rx.keys():
    if cur_rx[key] == max_rx[key]:
      print "[PASS] "+key+" rx value = "+max_rx[key]
    else:
      print "[FAIL] Current RX value = " +cur_rx[key]+ " (Required RX value = " +max_rx[key]+ ")"
else:
  print "Only root can run this, and you are %s with a id of %s" % (login, uid