Re: [lwip-users] Problem with memory management

[FreeRTOS Info]

On 03/02/2012 10:00, Walter Saegesser wrote:
> I encounter a severe problem with the memory manager (mem.c,
> MEM_USE_POOLS not set, LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT not set).
> 
> My buffer is approx 40kB. An SSL connection to a server on the internet
> does a big amount of allocations/deallocations (mostly small blocks).
> For receiving data from the server I need 1kB blocks.
> 
> It all works fine until all of a sudden the manager is no longer able to
> get a 1kB block and the ‘err’ counter of the mem-stats is counted up
> (every 100ms for about 15s until the system is reset by the watchdog).
> 
>  
> 
> In the debugger I have a real-time monitoring of the used ram
> (lwip_stats.mem.used). The value goes up and down, as expected,
> definitively no accumulation. The high-water-mark is at least 10kB below
> the heap size.
> 
> The system is multitasking. The task trying to get the 1kB block sleeps
> for a while if it fails, thus enabling other tasks to run and possibly
> free memory. However, the error is not recoverable and the system crashes.
> 
> If the systems runs into this situation (one task trying in vain to get
> a 1kB block), you can see the ‘used’ value go down to about 22kB, i.e.
> almost 18kB are free.
> 
>  
> 
> The problem arises always at almost the same amount of data received
> from the server, so I think it’s a systematic problem and not just
> accidental.
> 
> Could this be a bug or what else could be wrong?


If MEM_USE_POOLS is not set could this simply be memory fragmentation?


Regards,
Richard.

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