r13773@catbus: nickm | 2007-07-16 11:58:25 -0400

 Initial "constrained socket buffers" patch from coderman. needs tweaking.


svn:r10842

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/tor.1.in b/doc/tor.1.in
index 0589d45bcc..b66647dbdf 100644
--- a/doc/tor.1.in
+++ b/doc/tor.1.in
@@ -101,6 +101,33 @@ You probably don't need to adjust this. It has no effect on
 Windows since that platform lacks getrlimit(). (Default: 1000)
 .LP
 .TP
+\fBConstrainedSockets \fR\fB0\fR|\fB1\fR\fP
+If set, Tor will attempt to shrink the recv and xmit buffers for all 
+sockets to the size specified in \fBConstrainedSockSize\fP.  This is useful 
+for virtual servers and other environments where system level TCP
+buffers may be limited.  If you encounter the "Error creating network
+socket: No buffer space available" message you are likely experiencing
+this problem.
+
+The preferred solution is to have the admin increase the buffer pool for
+the host itself via /proc/sys/net/ipv4/tcp_mem or equivalent facility. 
+
+The DirPort option should also not be used if TCP buffers are scarce.  The
+cached directory requests consume additional sockets which exacerbates the
+problem.
+
+You should \fBnot\fP enable this feature unless you encounter the no buffer
+space available issue.  Reducing the TCP buffers affects window size for
+for the TCP stream and will reduce throughput in proportion to round trip
+time on long paths.
+.LP
+.TP
+\fBConstrainedSockSize \fR\fINUM\fP
+When \fBConstrainedSockets\fP is enabled the recv and xmit buffers for
+all sockets will be set to this limit.  Must be a value between 2048
+and 262144 in 1024 byte increments.  Default of 8192 is recommended.
+.LP
+.TP
 \fBControlPort \fR\fIPort\fP
 If set, Tor will accept connections on this port and allow those
 connections to control the Tor process using the Tor Control Protocol