RE: [lwip-users] Optimizations for applications requiring limited functionality.

[Roger Cover]

Greetings Simon,

I have not looked very far into what lwIP is doing internally. I know
that the function ip_output_if() is where my CPU is spending over 80% of
its time during my UDP transfers. I am using a Gigabit MAC/PHY, so
lwIP's transmission speed is no where near what the hardware can
sustain. There should not be any waiting for the hardware.

In fact, the Xilinx driver I have, from the reference design I started
with, does not even check to see if the MAC's FIFO is full. It just
blindly sends data to the MAC presuming the FIFO will be emptied faster
than it can be filled. This presumption is justified if the PHY has
negotiated a Gigabit connection. In my test setup, it has.

Is there something in particular you would like me to look into?

Regards,
Roger
-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf Of
Goldschmidt Simon
Sent: Tuesday, April 17, 2007 6:09 AM
To: Mailing list for lwIP users
Subject: RE: [lwip-users] Optimizations for applications
requiringlimitedfunctionality.


> Now that I have version 1.2.0 running, I have noticed a 
> decrease in performance (about 40%). Part of the decrease I 

Can you measure CPU load of 0.6.3 compared to 1.2.0? E.g. does lwIP
consume more
CPU cycles or is there some kind of slow-down due to lwIP waiting for
something?

Simon


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