From a113d4ee37f47c1eb3bad45cb53f8ad5434a8c1c Mon Sep 17 00:00:00 2001
From: deuce <>
Date: Thu, 2 Feb 2006 19:01:29 +0000
Subject: [PATCH] If the highwater mark is zero, and TCP_MAXSEG is supported
(BSD and Linux) Then autotune the highwater mark to be the MSS and never
send() a buffer larger than that.
---
src/sbbs3/main.cpp | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/src/sbbs3/main.cpp b/src/sbbs3/main.cpp
index 64d09d5dc2..e48e38bc93 100644
--- a/src/sbbs3/main.cpp
+++ b/src/sbbs3/main.cpp
@@ -1454,6 +1454,7 @@ void output_thread(void* arg)
sbbs_t* sbbs = (sbbs_t*) arg;
fd_set socket_set;
struct timeval tv;
+ ulong mss=IO_THREAD_BUF_SIZE;
thread_up(TRUE /* setuid */);
@@ -1468,13 +1469,36 @@ void output_thread(void* arg)
sbbs->output_thread_running = true;
sbbs->console|=CON_R_ECHO;
+#ifdef TCP_MAXSEG
+ /*
+ * Auto-tune the highwater mark to be the negotiated MSS for the
+ * socket (when possible)
+ */
+ if(!sbbs->outbuf.highwater_mark) {
+ socklen_t sl;
+ sl=sizeof(i);
+ if(!getsockopt(sbbs->client_socket, IPPROTO_TCP, TCP_MAXSEG, &i, &sl)) {
+ /* Check for sanity... */
+ if(i>100) {
+ sbbs->outbuf.highwater_mark=i;
+ lprintf(LOG_DEBUG,"Autotuning outbuf highwater mark to %d based on MSS",i);
+ mss=sbbs->outbuf.highwater_mark;
+ if(mss>IO_THREAD_BUF_SIZE) {
+ mss=IO_THREAD_BUF_SIZE;
+ lprintf(LOG_DEBUG,"MSS (%d) is higher than IO_THREAD_BUF_SIZE (%d)",i,IO_THREAD_BUF_SIZE);
+ }
+ }
+ }
+ }
+#endif
+
while(sbbs->client_socket!=INVALID_SOCKET && !terminate_server) {
/*
* I'd like to check the linear buffer against the highwater
* at this point, but it would get too clumsy imho - Deuce
*
* Actually, another option would just be to have the size
- * of the linear buffer equal to the MTU... any larger and
+ * of the linear buffer equal to the MSS... any larger and
* you could have small sends off the end. this would
* probobly be even clumbsier
*/
@@ -1503,6 +1527,9 @@ void output_thread(void* arg)
,node, avail, sizeof(buf));
avail=sizeof(buf);
}
+ /* If we know the MSS, use it as the max send() size. */
+ if(avail>mss)
+ avail=mss;
buftop=RingBufRead(&sbbs->outbuf, buf, avail);
bufbot=0;
}
--
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