| 470,24 → 470,36 |
|---|
| |
| macro TCP_set_persist socket { |
| |
| ;int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; |
| ;int tt; |
| ; |
| ;tp->t_flags &= ~TF_PREVVALID; |
| ; |
| ; First, check if retransmit timer is not set, retransmit and persist are mutually exclusive |
| |
| ; cmp [socket + TCP_socket.timer_retransmission] |
| |
| ; calculate RTO |
| |
| ; mov ecx, [socket + TCP_socket.t_srtt] |
| ; shr ecx, 2 |
| ; add ecx, [socket + TCP_socket.t_rttvar] |
| ; shr ecx, 1 |
| |
| ; and [socket + TCP_socket.t_flags], not TF_PREVVALID |
| |
| ;if (tcp_timer_active(tp, TT_REXMT)) |
| ; panic("tcp_setpersist: retransmit pending"); |
| ; |
| ;; Start/restart persistance timer. |
| ; |
| |
| ; Start/restart persistance timer. |
| |
| ;TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], TCPTV_PERSMIN, TCPTV_PERSMAX); |
| ;tcp_timer_activate(tp, TT_PERSIST, tt); |
| ; |
| ;if (tp->t_rxtshift < TCP_MAXRXTSHIFT) |
| ; tp->t_rxtshift++; |
| |
| ; cmp [socket + TCP_socket.t_rxtshift], TCP_MAXRXTSHIFT |
| ; jae @f |
| ; inc [socket + TCP_socket.t_rxtshift] |
| ; @@: |
| |
| } |
| |
| |
| |
| ; eax = rtt |
| ; ebx = socket ptr |
| |
| 494,6 → 506,61 |
|---|
| align 4 |
| TCP_xmit_timer: |
| |
| ;TODO: update srtt and rttvar |
| ;TODO: update stats |
| |
| cmp [ebx + TCP_SOCKET.t_rtt], 0 |
| je .no_rtt_yet |
| |
| ; srtt is stored as a fixed point with 3 bits after the binary point. |
| ; The following magic is equivalent of the smoothing algorithm in rfc793 with an alpha of .875 |
| ; (srtt = rtt/8 + srtt*7/8 in fixed point) |
| ; Adjust rtt to origin 0. |
| |
| push ecx |
| mov ecx, [ebx + TCP_SOCKET.t_srtt] |
| shr ecx, TCP_RTT_SHIFT |
| sub eax, ecx |
| dec eax |
| pop ecx |
| |
| add [ebx + TCP_SOCKET.t_srtt], eax |
| ja @f |
| mov [ebx + TCP_SOCKET.t_srtt], 1 |
| @@: |
| |
| ; We accumulate a smoothed rtt variance (actually, a smoothed mean difference), |
| ; then set the retransmit timer to smoothed rtt + 4 times the smoothed variance. |
| ; rttvar is stored as fixed point with 2 bits after the binary point. |
| ; The following is equivalent to rfc793 smoothing with an alpha of .75 |
| ; (rttvar = rttvar*3/4 + delta/4) (delta = eax) |
| |
| ; get abs(eax) |
| push edx |
| cdq |
| xor eax, edx |
| sub eax, edx |
| |
| mov edx, [ebx + TCP_SOCKET.t_rttvar] |
| shr edx, TCP_RTTVAR_SHIFT |
| sub eax, edx |
| pop edx |
| |
| add [ebx + TCP_SOCKET.t_rttvar], eax |
| ja @f |
| mov [ebx + TCP_SOCKET.t_rttvar], 1 |
| @@: |
| ret |
| |
| |
| .no_rtt_yet: |
| |
| push ecx |
| mov ecx, eax |
| shl ecx, TCP_RTT_SHIFT |
| mov [ebx + TCP_SOCKET.t_srtt], ecx |
| |
| shl eax, TCP_RTTVAR_SHIFT - 1 |
| mov [ebx + TCP_SOCKET.t_rttvar], eax |
| pop ecx |
| |
| ret |