[lwip-devel] [patch #7135] Significant etharp optimization for TX speed improvement

[Bill Auerbach]

Follow-up Comment #2, patch #7135 (project lwip):

This avoids searching that cache (if you mean the ARP table).  If you mean
something else, then I think it's not as good as this.  If it's done at the
pbuf level, didn't already pass the ARP tests?

I believe I tried with and without LWIP_NETIF_HWADDRHINT.  Where I added that
test to avoid the call to etharp_query, send 100,000 packets to a netif and
time how much is spent in all of the calls to etharp_query.  When I did this,
this was a big part of the total time to send a bunch of packets.

I didn't do the timing like this - I studied the total flow of sending a
packet and timed sending 1,000,000 packets while optimizing or removing calls
in the call tree where I could.

This is like the other patch - it's easy to test and if anyone else sees a
respectable gain then it's worth adding (as an option or otherwise).  The code
size increase here is tiny.

If it's not added, at least if it's asked for someone has something to try. 
Where are all of the people who asked over the year or 2 about speeding up
lwIP transmit speeds? :-)

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