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Index: head/sys/netinet/tcp_input.c
===================================================================
--- head/sys/netinet/tcp_input.c
+++ head/sys/netinet/tcp_input.c
@@ -212,11 +212,6 @@
&VNET_NAME(tcp_do_autorcvbuf), 0,
"Enable automatic receive buffer sizing");
-VNET_DEFINE(int, tcp_autorcvbuf_inc) = 16*1024;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_VNET | CTLFLAG_RW,
- &VNET_NAME(tcp_autorcvbuf_inc), 0,
- "Incrementor step size of automatic receive buffer");
-
VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(tcp_autorcvbuf_max), 0,
@@ -1449,13 +1444,16 @@
* The criteria to step up the receive buffer one notch are:
* 1. Application has not set receive buffer size with
* SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE.
- * 2. the number of bytes received during the time it takes
- * one timestamp to be reflected back to us (the RTT);
- * 3. received bytes per RTT is within seven eighth of the
- * current socket buffer size;
- * 4. receive buffer size has not hit maximal automatic size;
+ * 2. the number of bytes received during 1/2 of an sRTT
+ * is at least 3/8 of the current socket buffer size.
+ * 3. receive buffer size has not hit maximal automatic size;
*
- * This algorithm does one step per RTT at most and only if
+ * If all of the criteria are met we increaset the socket buffer
+ * by a 1/2 (bounded by the max). This allows us to keep ahead
+ * of slow-start but also makes it so our peer never gets limited
+ * by our rwnd which we then open up causing a burst.
+ *
+ * This algorithm does two steps per RTT at most and only if
* we receive a bulk stream w/o packet losses or reorderings.
* Shrinking the buffer during idle times is not necessary as
* it doesn't consume any memory when idle.
@@ -1472,11 +1470,10 @@
if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) &&
tp->t_srtt != 0 && tp->rfbuf_ts != 0 &&
TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) >
- (tp->t_srtt >> TCP_RTT_SHIFT)) {
- if (tp->rfbuf_cnt > (so->so_rcv.sb_hiwat / 8 * 7) &&
+ ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) {
+ if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) &&
so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) {
- newsize = min(so->so_rcv.sb_hiwat +
- V_tcp_autorcvbuf_inc, V_tcp_autorcvbuf_max);
+ newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max);
}
TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize);

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