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[lwip-users] lwipopts.h setting to boost throughput

From: Wing Kei Chow
Subject: [lwip-users] lwipopts.h setting to boost throughput
Date: Wed, 3 May 2006 18:41:51 +0800

I am using Lwip 1.1.1 on top of tun/tap in Linux platform. To test the throughput of lwip, I made lwip as a server sending as many packets as possible to a client and client measured the data rate. I found the throughput was only 10M and wanted to raise the throughput. So I increased the value of parameter TCP_SND_BUF in lwipopts.h to 4096 and the throughput increased up to 20Mbps. Then I further increased this parameter to larger value expecting to have higher throughput. However, when lwip receive request from the client and sent packets, lwip stopped suddenly.
In debugging, when sys_sem_signal() is executed in sent_tcp(), lwip stops. I suspect that the problem is related to pthread_cond_broadcast() which wakes up all other threads and is deadlock. Function sys_sem_signal() is in file sys_arch.c.  
The code of sys_sem_signal():
sys_sem_signal(struct sys_sem *sem)


  if (sem->c > 1) {
    sem->c = 1;


Can anybody solve this probelm?

By the way, how can I debug lwip with gdb to find where the program stopped?

Thank you very much!


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