• Josh Hunt's avatar
    tcp: add new tcp_mtu_probe_floor sysctl · c04b79b6
    Josh Hunt authored
    The current implementation of TCP MTU probing can considerably
    underestimate the MTU on lossy connections allowing the MSS to get down to
    48. We have found that in almost all of these cases on our networks these
    paths can handle much larger MTUs meaning the connections are being
    artificially limited. Even though TCP MTU probing can raise the MSS back up
    we have seen this not to be the case causing connections to be "stuck" with
    an MSS of 48 when heavy loss is present.
    
    Prior to pushing out this change we could not keep TCP MTU probing enabled
    b/c of the above reasons. Now with a reasonble floor set we've had it
    enabled for the past 6 months.
    
    The new sysctl will still default to TCP_MIN_SND_MSS (48), but gives
    administrators the ability to control the floor of MSS probing.
    Signed-off-by: default avatarJosh Hunt <johunt@akamai.com>
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    c04b79b6
ipv4.h 5.57 KB