[lwip-users] Re: [lwip] Pbuf Pool

[James Roth]

Mumtaz Ahmad wrote:

>Hi
>
>I am usiung lwip on trimedia board . I am facing a problem when the ethernet
>interface transfers a buffer to lwip .I am experiencing a data loss as
>POOL_BUFFS are not available all the time . I have tried to change the
>number of POOL Buffers but with no success . Most failures are due to free
>lock problem. I tried to understand it but somehow i ahave been unable to
>understand all this caching mechanism and i donot know why i get pbuff pool
>locked often . Any suggestion in this regard ?
>
>Regards
>Mumtaz Ahmad
>       _o
>    _< \_
>   (_) >(_)
>   -------------
>
>
>[This message was sent through the lwip discussion list.]
>
I have seen the pool locked in this case (using a debugger):

    1.  A pbuf_* function is called.  It locks the pool.
    2.  The pbuf_ function indirectly results in a call to sys_sem_* or 
similar.
    3.  The sem function results in a call to a timeout function.
    4.  Finally, the timeout function calls a pbuf_* function.  The pool 
is still locked from step 1.

Does this sound right folks?

 From what I can tell, it's not really a problem.  When I made my 
sys_arch functions more accurate in terms of timing, this happened far 
less often.

-- 
James Roth
Shugyo Design Technologies
http://www.shugyodesign.com/



[This message was sent through the lwip discussion list.]