Re: zero copy

[Steven Whitehouse <steve@chygwyn.com>]

Hi,

See sock_no_sendpage() in linux/net/core/sock.c for when network
protocols don't support zerocopy and tcp_sendpage() in
linux/net/ipv4/tcp.c for an example where it is supported. The
NETIF_F_SG and TCP_ZC_CSUM_FLAGS test in the latter function
is probably what you are after?

Steve.

On Tue, Dec 06, 2005 at 04:09:30AM -0800, kernel coder wrote:
> hi,
> i'm trying to track the code flow of sendfile system call.Mine
> ethernet card doesn't have scatter gather and checksum calculation
> features.So stack should be making a copy of data.
> 
> Please tell me where in sendfile code flow,check for scatter gather
> and cecksum features is made so that stack can decide whether to copy
> data from user space or not.
> 
> lhrkernelcoder
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