-----Original Message----- From: kernelnewbies-bounces@kernelnewbies.org [mailto:kernelnewbies-bounces@kernelnewbies.org] On Behalf Of ratheesh kannoth Sent: Wednesday, February 26, 2014 11:28 PM To: kernelnewbies@kernelnewbies.org Subject: Fwd: zero copy with PACKET_MMAP
Hi ,
The link
https://www.kernel.org/doc/Documentation/networking/packet_mmap.txt talks about achieving zero copy. But i find a deep packet copy ( of length snaplen= skb->len ) here http://lxr.free-electrons.com/source/net/packet/af_packet.c#L1841.
Is there anything missing/wrong in my understanding ?
Thanks, Ratheesh
It's "zero copy" in that it is not necessary to copy the contents of the kernel resident socket buffer to user space in order for user space to read it. But you are not missing anything. There is still a copy involved in order to copy the packet to the socket ring buffer. Jeff Haran