Bill Fink wrote:
<snip>

Yes, every individual Linux network administrator can re-create the
wheel by devising their own scripts, but it makes much more sense
to me to implement a simple general kernel mechanism once that could
be used generically, than to have hundreds (or thousands) of Linux
network administrators each having to do it themselves (perhaps
multiple times if they have a variety of types of systems and types
of NICs).

The ethtool interface is pretty generic, even if the names aren't.
Here's some Python code I just knocked up which demonstrates how
to get a set of named stats.  It shouldn't be terribly hard to
extend this to saving and subtracting stat sets.

Ben.

import array, fcntl, os, socket, struct

SIOCETHTOOL = 0x8946

ETH_GSTRING_LEN = 32
ETH_SS_STATS = 1

ETHTOOL_GDRVINFO = 0x00000003
ETHTOOL_GSTRINGS = 0x0000001b
ETHTOOL_GSTATS = 0x0000001d

def ethtool(sock, name, buf):
    ifreq = struct.pack('16sP', name, buf.buffer_info()[0])
    fcntl.ioctl(sock.fileno(), SIOCETHTOOL, ifreq)

def ethtool_gdrvinfo(sock, name):
    cmd = struct.pack('=I', ETHTOOL_GDRVINFO)
    buf = array.array('c', cmd)
    format = '=32s32s32s32s32x12xIIIII'
    buf.extend('\0' * struct.calcsize(format))
    ethtool(sock, name, buf)
    return dict(zip(['driver', 'version', 'fw_version', 'bus_info',
                     'n_priv_flags', 'n_stats', 'testinfo_len',
                     'eedump_len', 'regdump_len'],
                    struct.unpack(format, buf[len(cmd):])))

def ethtool_gstrings(sock, name, string_set, count):
    cmd = struct.pack('=II', ETHTOOL_GSTRINGS, string_set)
    buf = array.array('c', cmd)
    buf.extend('\0' * (4 + count * ETH_GSTRING_LEN))
    ethtool(sock, name, buf)
    def nth_string(buf, n):
        data = buf[12 + n * ETH_GSTRING_LEN : 12 + (n + 1) * ETH_GSTRING_LEN]
        return data.tostring().replace('\0', '')
    return [nth_string(buf, n) for n in range(count)]

def ethtool_gstats(sock, name, count):
    cmd = struct.pack('=I', ETHTOOL_GSTATS)
    buf = array.array('c', cmd)
    buf.extend('\0' * (4 + count * 8))
    ethtool(sock, name, buf)
    def nth_stat(buf, n):
        data = buf[8 + n * 8 : 8 + (n + 1) * 8]
        return struct.unpack('=Q', data)[0]
    return [nth_stat(buf, n) for n in range(count)]

if __name__ == '__main__':
    import sys
    name = sys.argv[1]
    sock = socket.socket()
    drvinfo = ethtool_gdrvinfo(sock, name)
    count = drvinfo['n_stats']
    print dict(zip(ethtool_gstrings(sock, name, ETH_SS_STATS, count),
                   ethtool_gstats(sock, name, count)))

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.