|Subject:||Re: [lwip-devel] Fwd: Re: TCP errors going from 1.4.1 to 2.0.3|
|Date:||Thu, 2 Nov 2017 11:40:20 +0100|
|User-agent:||Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0|
Bill Auerbach wrote:
I've just spent 2 hours again with cached pointers and flushing on Ethernet TX and RX and it mostly works - it's just not error free.
What do you mean by "not error free"? Invalid checksums in your TX packets or dup-acks + retransmissions (which would be errors in the RX path)?
When flushing caches, it's important that struct pbuf is cache-aligned, i.e. flushing/invalidating the payload region does not interfere with the rest of the struct.
As to copying data into application buffers: that part may be true, but before you get the rx callback, lwIP already processes the headers. I'm not sure how performance is affected when this is done uncached.
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