Linux 内核网络协议栈 ------ TCP拥塞状态机 tcp_fastretrans_alert
这里主要说的是TCP拥塞情况下的状态状态处理/*Processanevent,whichcanupdatepackets-in-flightnottrivially.*Maingoalofthisfunctionistocalculatenewestimateforleft_out,*takingintoaccountbothpacketssittinginreceiver'sbufferand*