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

[Roger Cover]

Greetings Timmy,
 
I have rewritten the checksum routine in assembler for my processor (as 
recommended by Adam Dunkels in the thread "Gigabit Ethernet and lwIP"). It is 
not my experience that this is the largest consumer of CPU cycles. 
ip_output_if() seems to be where my application spends over 80% of its time on 
UDP transfers, but this is called after the checksum calculation is completed. 
I have not profiled the TCP/IP transfer yet, just measured its total time.
 
Regards,
Roger 
________________________________

From: address@hidden [mailto:address@hidden On Behalf Of Timmy Brolin
Sent: Monday, April 16, 2007 12:11 PM
To: Mailing list for lwIP users
Subject: Re: RE : [lwip-users] Optimizations forapplications 
requiringlimitedfunctionality.


If you want to increase performance in a limited functionality application, 
perhaps you don't need the UDP checksum?
I think most of the CPU cycles related to TCP or UDP communication are consumed 
in the checksum calculation.

/Timmy

Roger Cover wrote: 

        Greetings Frédéric,
        
        The performance decrease I measured was relative to version 0.6.3 of 
lwIP. The measurement is the total transfer time for a 33560192 byte data set 
from my instrument to an application on my PC using TCP/IP. The time was 13.98 
seconds for lwIP 0.6.3 and 19.56 seconds for lwIP 1.2.0. I am using the same 
"driver", with minor modifications to accommodate the API changes in the lwIP 
code from 0.6.3 to 1.2.0, and the same applications on the PC and my embedded 
PPC405 processor. Removing the statistics improved the performance, but did not 
recover the entire 40%.
        
        I will let you know what improvements I get from the lwipopts.h changes 
you suggested.
        
        Regards,
        Roger
        -----Original Message-----
        From: address@hidden [mailto:address@hidden On Behalf Of Frédéric BERNON
        Sent: Saturday, April 14, 2007 3:03 AM
        To: Mailing list for lwIP users
        Subject: RE : [lwip-users] Optimizations for applications 
requiringlimitedfunctionality.
        
        Hi Roger,
        
          

                I have noticed a decrease in performance (about 40%)
                    

        40% ???? Was is this measure ? Max bandwidth on output, number of 
cycles used, footprint? If I understand what you wrote, it was on max 
bandwidth? And just due to statistics? Seems strange...
        
        
        
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