Re: [lwip-users] Reg: Optimum Performance - lwip +PPP

[S. Ali Tokmen]

Hello

 

There are two points of view:

• If you need very low latency (very fast response), you should avoid buffering any output and send data out as soon as you have it. This will also result in a lot of data waiting to be sent, therefore a lot of small packets in the lwIP stack; that's why you should set the number of PBUF and NETBUF high. The performance I've been able of measuring with this strategy is a Telnet server responding in less than 2ms in all cases (and an average response time of 1ms over 700 requests).
• If you need very high throughput rates (a lot of KBs per second), buffering is a good strategy. When implementing an HTTP server, I've found out that buffering the output until ~56 KB and then calling send() was resulting in the best performance (around 2MB/s). In this case, since it's your software that does the buffering, changing memory settings for lwIP is probably not necessary. IMPORTANT: don't call send() with more than (64K - TCP_HEADER) bytes, it will not work correctly.

Hope this helps

S. Ali Tokmen
http://ali.tokmen.com

 

GSM (fr): +33 66 43 00 555 [Bouygues Telecom]
GSM (tr): +90 555 266 52 73 [Avea]

 

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----- Original Message -----

From: Nandakumar KS

To: 'Mailing list for lwIP users'

Sent: Wednesday, October 03, 2007 6:15 AM

Subject: RE: [lwip-users] Reg: Optimum Performance - lwip +PPP

Hi,

 

Thanks for your mail.

Yes. I am using BF processor and VisualDSP.

 

Our application needs to send huge amount of data to FTP server.

Currently we are sending to FTP server in terms of 1024 bytes. I.e. we are calling “send” API in terms of 1024bytes

 

So, which will be the better option i.e. to send the entire data at once or to send it in terms of small chunks? And what will be the optimum values in lwipopts.h file for both the cases?

 

Regards

Nandakumar KS

 

 

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From: address@hidden [mailto:address@hidden On Behalf Of S. Ali Tokmen
Sent: Tuesday, October 02, 2007 6:33 PM
To: address@hidden; Mailing list for lwIP users
Subject: Re: [lwip-users] Reg: Optimum Performance - lwip +PPP

 

Hello

 

How does your application work: do you tend to send large amounts of data at once, a lot of packets with small amounts of data, ... ?

 

There's a file called lwipopts.big.h (in C:\Program Files\Analog Devices\VisualDSP 5.0\Blackfin\lib\src\lwip\contrib\ports\ADSP-Blackfin\proj) , in which you'll find settings for applications sending out laaaaaaarge amounts of data.

 

PS: I hope you're still using BF processors and VisualDSP, otherwise I can also send you the file

 

Cheers

S. Ali Tokmen
http://ali.tokmen.com

 

GSM (fr): +33 66 43 00 555 [Bouygues Telecom]
GSM (tr): +90 555 266 52 73 [Avea]

 

My AIM, ICQ, MSN Messenger, and Yahoo IM
contact details are on http://contact.ali.tokmen.com/

 

 

----- Original Message -----

From: Nandakumar KS

To: 'Mailing list for lwIP users'

Sent: Tuesday, October 02, 2007 2:34 PM

Subject: [lwip-users] Reg: Optimum Performance - lwip +PPP

 

Hi,

 

I am using lwIP with PPP and it is working fine. Can anyone suggest the optimum values in the opt.h file, so that data transfer performance can be increased? Aim is to increase the data transfer rate.

 

Regards

Nandakumar KS

 

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