RE: [lwip-users] Transferring large data fast and pointing pbufs directly to Ethernet receive buffers

[Bill Auerbach]

> > I see this is the way to go.  I'll have to see if I can figure how to
> > release the ETH buffer the pbuf points to when the pbuf has been
> processed.
> 
> Yes I added a hook in the lwIP code in my tree for this. A proper solution
> will take some discussion and isn't there now (nor will it be for 1.3.0).
> 
> As Simon said, the alternative is just to receive into static buffers and
> then memcpy everything to pbufs, with the obvious space and speed hit.

OK.  I was wondering about checking in pbuf_free if payload is within the
ETH buffer area (it's contiguous and has compile-time bounds).  If I see an
ETH buffer address, then mark the buffer as free (you update the BD which
contains the buffer address).  I'd have to search the BDs to find the owner
of the buffer - this may take more time than memcpying the payload. :)

I'll do the memcpy for now and see how it goes.  I don't think memcpy's are
going to be the bottleneck.  Using half the RAM would have been nice.

Thanks to all who responded.  You've been most helpful.

Bill