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From: | Gary Olson |
Subject: | [lwip-users] TCP_WINDOW_SIZE Limit |
Date: | Fri, 17 Oct 2008 10:15:13 -0400 |
Hi,
I have been trying to increase my bandwidth by increasing the TCP_WINDOW_SIZE
on the PC. I have already increased the TCP_WINDOW on LWIP. I
changed the TCP_WINDOW_SIZE to a much higher level in the Regedit TCP
Parameters area to a very large value of 131400. However, The
actual window size is controlled in the following code snippet in my MSVC C++
Program shown here: //buffsize = 25000;
Failed // now will
try to increase packet size put here at 20000. buffsize = 20000; //
this does not increase speed I think works .49 seconds for this test. //buffsize =
8195; // since no real increase in speed I put at here. result =
setsockopt(m_socket[i], SOL_SOCKET, SO_SNDBUF, ( char * ) &buffsize,
sizeof(buffsize)); if ( result !=
SOCKET_ERROR ) {
printf("PASSED socketopt i = %d /t %d decimal\n", i, buffsize); } else {
printf("Error setting send RecvBuf /t i = %d \n");
} What I find is that when I gradually increase my
TCP_WINDOW_SIZE the SO_SNDBUF value from 8195 to 25000 I start failing at
25000. It passed at 20000. So I thought I would try changing some of the Parameters
related to TCP buffers. I added these lines below to my MSS file that
change the LWIP Settings: BEGIN LIBRARY PARAMETER LIBRARY_NAME = lwip PARAMETER LIBRARY_VER = 3.00.a PARAMETER PROC_INSTANCE = microblaze_0 PARAMETER tcp_mss = 8560 PARAMETER mem_size = 1000000 PARAMETER pbuf_pool_bufsize = 8600 PARAMETER tcp_wnd = 60000 PARAMETER tcp_snd_buf = 40000 PARAMETER tcp_tx_checksum_offload = true PARAMETER tcp_rx_checksum_offload = true PARAMETER udp_ttl = 255 PARAMETER ip_default_ttl = 255 PARAMETER memp_n_tcp_seg = 512 PARAMETER memp_n_pbuf = 32 PARAMETER pbuf_pool_size = 512 PARAMETER memp_n_tcp_pcb = 64 END This
did not help however. It still works when at 20000 but at 25000 it
fails. Is there anything that can be changed in LWIP That
may be able to increase my window size on the PC. Or maybe it has to do
with the Xilinx LLTEMAC hardware. The size of the Memory
on the Receive and transmit is 8192. I can not increase it any more in
this design. Thank
You,
Gary Olson |
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