Re: [RTnet-developers] Ethernet IP

[Glen W. <gl...@je...>]

Jan,

On you last comment below about pre allocating buffers, I am trying to find
where in the RTAI examples it show that?

Glen


On 9/28/10 5:35 PM, "Jan Kiszka" <jan...@we...> wrote:

> Am 28.09.2010 23:17, Glen Wernersbach wrote:
>> Jan,
>> 
>> My basic concern was to keep the data flowing from the NIC to my program as
>> close to hard real time as possible. I know doing Linux calls can break hard
>> real time especially when I want to receive a UDP packet every 1ms.
> 
> Is that UDP packet part of your control loop? Why do you need the whole
> opener stack then? Or is there more?
> 
>> 
>> The only thing Ethernet IP really gives you real time is optional support
>> for the Ethernet 1588 timing standard so you know what the jitter was in
>> receiving the packet over the Ethernet line. The 1588 support is not yet
>> implemented in opener. The rest is just a protocol for handling critical
>> data over TCP and UDP. Unfortunately, I have a device that needs to work on
>> Allen Bradley controllers which only support this real time protocol.
>> 
>> All I want to do is replace the Linux calls in networkhandler.c
>> (socket,bind,listen...) with RTAI real time calls.
> 
> Additionally, you will have to configure the socket resources, namely
> how many buffers each socket should pre-allocate for its real-time
> operation (that's the major difference to normal networking stack that
> do on-demand allocations). See the examples.
> 
> Jan
> 

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