[ECOS] Re: Few questions on lwip stack

[Sergei Gavrikov]

On Wed, 17 Nov 2010, Alexander Aganichev wrote:

> On Tue, Nov 16, 2010 at 6:18 PM, Alexander Aganichev
> <aaganichev@gmail.com> wrote:
>> Now I have a problem that lwip sometimes ignores IP frames from PC
>> which cause PC to retransmit frame after two seconds which is not
>> acceptable. This happens not under heavy load. Never saw anything
>> similar on previous lwip version. The response time on ICMP is very
>> good and I don't see any delay or ignorance... Â Just wondering if
>> anyone saw something similar and have ideas where to dig?
>
> It looks like tcp_tmr() is not executed in sequential mode and this
> cause the problem. Can it just be started from tcpip_thread() like
> other timers?

Hi,

Can you provide your ecm file/test? Of curiosity I tried eCos `tcpecho'
test under some load and I did not observe the same fading.

Having no real H/W  I used something virtual

   eCos:     CVS updated
   Host:     Linux
   Target:   pc_rltk8139
   Template: lwip_eth
   Startup:  RAM
   Hardware: QEMU
   Test:     tcpecho
   Run land: GDB (i386-elf-gdb)

   Only changed:

   cdl_option CYGFUN_LWIP_MODE_SIMPLE {
       user_value 0
   };
   cdl_option CYGFUN_LWIP_MODE_SEQUENTIAL {
       user_value 1
   };

   Stress Fu:

   % strings /dev/urandom | nc host port   ;# port was mapped on 7th

I saw l-o-o-o-ng and continuous 'matrix' in terminal. No fading. After
STOP/CONT (I got a resumption of the run as I expected) Well, it was
lazy and not accurate test, it was virtual H/W  (but real S/W) and I
could not reproduce the issue for my environment. However, I guess the
packets could be lost (I was looking only for any long fading and I did
not plan to dive in the dumps of network traffic). Also, I call that
default CDL options (like mine) cannot be suitable for stress conditions
(i.e.  default sizes of net buffers, the stack sizes, etc.).  Seek the
posts near the time of porting new LWIP version, please, I hope that
Simon gave some advices.

Sergei

> WBR, Alexander
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