• Robert Shearman's avatar
    mpls: Packet stats · 27d69105
    Robert Shearman authored
    Having MPLS packet stats is useful for observing network operation and
    for diagnosing network problems. In the absence of anything better,
    RFC2863 and RFC3813 are used for guidance for which stats to expose
    and the semantics of them. In particular rx_noroutes maps to in
    unknown protos in RFC2863. The stats are exposed to userspace via
    AF_MPLS attributes embedded in the IFLA_STATS_AF_SPEC attribute of
    RTM_GETSTATS messages.
    
    All the introduced fields are 64-bit, even error ones, to ensure no
    overflow with long uptimes. Per-CPU counters are used to avoid
    cache-line contention on the commonly used fields. The other fields
    have also been made per-CPU for code to avoid performance problems in
    error conditions on the assumption that on some platforms the cost of
    atomic operations could be more expensive than sending the packet
    (which is what would be done in the success case). If that's not the
    case, we could instead not use per-CPU counters for these fields.
    
    Only unicast and non-fragment are exposed at the moment, but other
    counters can be exposed in the future either by adding to the end of
    struct mpls_link_stats or by additional netlink attributes in the
    AF_MPLS IFLA_STATS_AF_SPEC nested attribute.
    Signed-off-by: default avatarRobert Shearman <rshearma@brocade.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    27d69105
internal.h 4.63 KB