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[lwip-users] Re:Re: Re: retransmission every 9 pacakets.

From: Yang
Subject: [lwip-users] Re:Re: Re: retransmission every 9 pacakets.
Date: Wed, 19 Sep 2007 08:33:59 +0800

Hi all

  for this two days, fallowing Kieran's advice,I try to set the the right timer 
Thought it still not mach to real time clock now, but it seem to work some how! 
 I set this 
#define TCP_SLOW_INTERVAL      (10*TCP_TMR_INTERVAL)    //originally  2
 the speed is double, upto 600k.
And then fallow Dave Kitchen's advice,I enlarge my send buf
#define TCP_SND_BUF                     1024*32
this make the speed upto 700k.

  (Dave Kitchen told me in email:"I think I fixed this by making sure I had at 
least two buffers 
outstanding in the transmission pool - I think the defaults for lwip set 
the queue length to 4 (I run 6) but you also need to pass at least 
2*TCP_MSS of data into the netconn_write() calls (or, presumably, the 
socket interface equivalent).")
        But, the retrans is still there every 9 packages. In the trace, I can 
see the TCP_SLOW_INTERVAL make lwip wait half shorter time and retrans. I can't
figure out why changing  TCP_SND_BUF help!
    Once I make the timer mach the real clock, I will retprot the result again.

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