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Improve performance on long fat networks (LFNs)

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On Linux, the TCP send buffer size is increased to 32768 if it is less
that this (which it normally is). This however has the effect of disabling
dynamic buffer sizing, leading to a maximum available bandwidth of

max_bandwidth = 262144 (bits) / round_trip_time (secs)

This is not noticeable on a LAN with an RTT of around 0.5ms, but
very noticeable on a WAN with an RTT of 0.25s.

Comments in the config file and manpage in this area are improved, as
is the logging if the parameters are actually set.

(cherry picked from commit b23d6f89d5)
This commit is contained in:
matt335672 2024-01-11 11:53:54 +00:00
parent fc34c2b4c8
commit 40b0eaf455
4 changed files with 29 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
common/os_calls.c
View File

@ -434,23 +434,6 @@ g_tcp_socket(void)
}
}
option_len = sizeof(option_value);
if (getsockopt(rv, SOL_SOCKET, SO_SNDBUF, (char *)&option_value,
&option_len) == 0)
{
if (option_value < (1024 * 32))
{
option_value = 1024 * 32;
option_len = sizeof(option_value);
if (setsockopt(rv, SOL_SOCKET, SO_SNDBUF, (char *)&option_value,
option_len) < 0)
{
LOG(LOG_LEVEL_ERROR, "g_tcp_socket: setsockopt() failed");
}
}
}
return rv;
}

4
docs/man/xrdp.ini.5.in
View File

@ -177,7 +177,9 @@ If set to \fB1\fP, \fBtrue\fP or \fByes\fP, no buffering will be performed in th
\fBtcp_send_buffer_bytes\fP=\fIbuffer_size\fP
.TP
\fBtcp_recv_buffer_bytes\fP=\fIbuffer_size\fP
Specify send/recv buffer sizes in bytes. The default value depends on operating system.
Specify send/recv buffer sizes in bytes. The default value depends on
the operating system. It is recommended not to set these on systems with
dynamic TCP buffer sizing
.TP
\fBtls_ciphers\fP=\fIcipher_suite\fP

5
xrdp/xrdp.ini.in
View File

@ -35,7 +35,10 @@ tcp_nodelay=true
; if the network connection disappear without close messages the connection will be closed
tcp_keepalive=true
; set tcp send/recv buffer (for experts)
; set tcp send/recv buffer
; These parameters are largely historic. On systems with dynamic TCP
; buffer sizes, setting them manually will either impact performance or
; waste memory
#tcp_send_buffer_bytes=32768
#tcp_recv_buffer_bytes=32768

46
xrdp/xrdp_listen.c
View File

@ -716,47 +716,45 @@ xrdp_listen_process_startup_params(struct xrdp_listen *self)
if (startup_params->tcp_send_buffer_bytes > 0)
{
bytes = startup_params->tcp_send_buffer_bytes;
LOG(LOG_LEVEL_INFO, "setting send buffer to %d bytes",
bytes);
if (g_sck_set_send_buffer_bytes(ltrans->sck, bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error setting send buffer");
}
else if (g_sck_get_send_buffer_bytes(ltrans->sck, &bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error getting send buffer");
}
else if (bytes != startup_params->tcp_send_buffer_bytes)
{
LOG(LOG_LEVEL_WARNING, "send buffer set to %d "
"bytes but %d bytes requested", bytes,
startup_params->tcp_send_buffer_bytes);
}
else
{
if (g_sck_get_send_buffer_bytes(ltrans->sck, &bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error getting send "
"buffer");
}
else
{
LOG(LOG_LEVEL_INFO, "send buffer set to %d "
"bytes", bytes);
}
LOG(LOG_LEVEL_INFO, "send buffer set to %d bytes", bytes);
}
}
if (startup_params->tcp_recv_buffer_bytes > 0)
{
bytes = startup_params->tcp_recv_buffer_bytes;
LOG(LOG_LEVEL_INFO, "setting recv buffer to %d bytes",
bytes);
if (g_sck_set_recv_buffer_bytes(ltrans->sck, bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error setting recv buffer");
}
else if (g_sck_get_recv_buffer_bytes(ltrans->sck, &bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error getting recv buffer");
}
else if (bytes != startup_params->tcp_recv_buffer_bytes)
{
LOG(LOG_LEVEL_WARNING, "recv buffer set to %d "
"bytes but %d bytes requested", bytes,
startup_params->tcp_recv_buffer_bytes);
}
else
{
if (g_sck_get_recv_buffer_bytes(ltrans->sck, &bytes) != 0)
{
LOG(LOG_LEVEL_WARNING, "error getting recv "
"buffer");
}
else
{
LOG(LOG_LEVEL_INFO, "recv buffer set to %d "
"bytes", bytes);
}
LOG(LOG_LEVEL_INFO, "recv buffer set to %d bytes", bytes);
}
}
}