lwip-users
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [lwip-users] tcp_write with zero-copy


From: Christiaan Simons
Subject: Re: [lwip-users] tcp_write with zero-copy
Date: Mon, 31 Oct 2005 12:51:53 +0100


> i'm using the raw-interface with lwip 1.1.0 and want to avoid the
> buffer-copy at tcp_write.

The doc/rawapi.txt says the copy argument should be 0 in this case.
My guess is you cannot avoid copying because TCP must queue/dequeue
output data for flow control purposes.

> Is there a regular path to deliver the data by giving a
> PBUF_TRANSPORT instead of a raw data buffer to
> tcp_write (or another tcp_output function) just like in sending udp-data,
> or do i have to patch the sources to do this ?

I won't recommend bypassing the transport layer, as far as I understand
PBUF_TRANSPORT is reserved for internal usage.

> (e.h. use a special value of the copy-flag to just assume the buffer
> being a pbuf)

That might be a usefull feature, many applications do have a notion of
pbuf(chains).
Please note creating your own lwip branch can be quite cumbersome,
to keep up with future fixes / changes. Maybe Kieran can comment on this.

Bye,

Christiaan Simons

Hardware / Software Engineer
Axon Digital Design

+31 (0)13 511 66 66
+31 (0)13 511 41 51

http://www.axon.tv



This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the system manager.
This message contains confidential information and is intended only for the
individual named.  If you are not the named addressee you should not
disseminate, distribute or copy this e-mail.





reply via email to

[Prev in Thread] Current Thread [Next in Thread]