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

[Timmy Brolin]

That sounds very strange. Are your sure?
When I rewrote the checksum routine in assembly, I doubled the total 
performance of our TCP/IP stack.
For UDP communications, the only loop of any significance I can think of 
is the checksum routine.
Regards,
Timmy Brolin


Roger Cover wrote:

> 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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