• Xin Long's avatar
    sctp: implement prsctp PRIO policy · 8dbdf1f5
    Xin Long authored
    
    
    prsctp PRIO policy is a policy to abandon lower priority chunks when
    asoc doesn't have enough snd buffer, so that the current chunk with
    higher priority can be queued successfully.
    
    Similar to TTL/RTX policy, we will set the priority of the chunk to
    prsctp_param with sinfo->sinfo_timetolive in sctp_set_prsctp_policy().
    So if PRIO policy is enabled, msg->expire_at won't work.
    
    asoc->sent_cnt_removable will record how many chunks can be checked to
    remove. If priority policy is enabled, when the chunk is queued into
    the out_queue, we will increase sent_cnt_removable. When the chunk is
    moved to abandon_queue or dequeue and free, we will decrease
    sent_cnt_removable.
    
    In sctp_sendmsg, we will check if there is enough snd buffer for current
    msg and if sent_cnt_removable is not 0. Then try to abandon chunks in
    sctp_prune_prsctp when sendmsg from the retransmit/transmited queue, and
    free chunks from out_queue in right order until the abandon+free size >
    msg_len - sctp_wfree. For the abandon size, we have to wait until it
    sends FORWARD TSN, receives the sack and the chunks are really freed.
    Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    8dbdf1f5
chunk.c 9.82 KB