zero copy.

Hi,

Is linux able to do zero copy?

I remember from previous discussions that there was always a camp that would claim that the copy was free because of the checksum, and/or the other way around. And warming the cache on input would prove to eliminate almost all overhead.

I have an application where the bulk of the data is NOT generated or consumed by the CPU, in fact, the CPU does not have enough bandwidth to move all the data. We really need to have the DMA-devices go and get the data for themselves....

So far, I'm finding more or less unavoidable copy to/from user calls in both the tcp send and the tcp recieve path.....

Suggestions?

Roger.

** [email protected] ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
* There are old pilots, and there are bold pilots. 
* There are also old, bald pilots. 

You can do zero copy on TX by using sendfile() or writing a kernel module. Zero copy on RX is not directly supported by the standard network stack. It's possible to do it via a kernel module again, but very hackish.

-Andi