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[lwip-users] Slow sending speed
From: |
Sebastian |
Subject: |
[lwip-users] Slow sending speed |
Date: |
Mon, 22 Dec 2008 23:51:54 +0100 |
User-agent: |
KMail/1.9.6 (enterprise 0.20070907.709405) |
Hello,
as the title already says, I've got a problem with the sending speed, which is
extremly slow. My platform is a LPC2468 Controller from NXP with an ARM
Core.
It seems the problem is that lwIP sometimes holds back packets and waits for
the next ACK of the packet just sent. According to a typical TCP session, the
remote station expects a second packet and waits for 200ms before it's sends
the ACK. After that, lwIP will send the next packets.
Here is the log of Wireshark:
No. Time Source Dest. Protocol Info
2873 0.220744 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2874 0.221078 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2875 0.221095 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=515073 Win=65535 Len=0
2876 0.221912 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2877 0.353007 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2878 0.353065 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=517121 Win=65535 Len=0
2879 0.353277 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2880 0.546842 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=518145 Win=65535 Len=0
2881 0.547778 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2882 0.548066 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2883 0.548089 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=520193 Win=65535 Len=0
2884 0.548904 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2885 0.549227 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2886 0.549244 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=522241 Win=65535 Len=0
2887 0.550089 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2888 0.765583 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=523265 Win=65535 Len=0
2889 0.766469 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2890 0.766782 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2891 0.766801 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=525313 Win=65535 Len=0
2892 0.767610 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2893 0.767943 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2894 0.767960 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=527361 Win=65535 Len=0
2895 0.768778 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2896 0.846978 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2897 0.847028 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=529409 Win=65535 Len=0
2898 0.847265 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2899 0.984325 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=530433 Win=65535 Len=0
2900 0.985204 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2901 0.985516 lwIP .net ESP ESP (SPI=0x0e0e0e0e)
2902 0.985535 .net lwIP TCP udt_os > ndmp [ACK] Seq=1048577
Ack=532481 Win=65535 Len=0
Here are the options I used:
#define TCP_WND 2048
#define TCP_MSS 1024
#define MEMP_NUM_PBUF 32
#define PBUF_POOL_SIZE 32
#define MEMP_NUM_TCP_SEG 32
#define TCP_SND_BUF 2048
#define TCP_SND_QUEUELEN (16 * (TCP_SND_BUF/TCP_MSS)) * 2
#define TCP_SNDLOWAT 1024
Maybe someone has an idea.
Greetings, Sebastian
- [lwip-users] Slow sending speed,
Sebastian <=