Re: [PATCH] sendfile() and UDP socket

Hi All,

I'm sorry for this late reply but I was out of Internet access during one month.
So if my understanding is correct, sendfile() over UDP can't be used
to send a file > 64 ko in one system call, as each request must fit in
one UDP packet.

However is it expected that sendfile() returns 64Ko but sends nothing
over the network when we are performing this particular case
(file>64ko)? should it return 0?

Thanks in advance,
Johann

On Wed, Sep 24, 2008 at 6:53 AM, Bill Fink [off-list ref] wrote:

quoted

On Tue, 23 Sep 2008, Herbert Xu wrote:

quoted

On Tue, Sep 23, 2008 at 10:27:10AM +0400, Evgeniy Polyakov wrote:

quoted

On Tue, Sep 23, 2008 at 12:54:27PM +0800, Herbert Xu (herbert@gondor.apana.org.au) wrote:

quoted

I think this dicussion is moot since the only time you want to use
sendfile is for bulk transfers and these days anybody designing new
applications that does bulk transfers over UDP should be taken out
and shot.

One can protect himself pointing how slow may be memory bus in some
hardware setup, which completely does not allow to perform any copy.

Yes but bulk transfers over UDP is a bad idea regardless of how
slow your bus is :)

So what application needs this?

It seems it might be useful for a video server.  The one thing that
seems to be missing from the sendfile() semantics is a message size
to be used for splitting the file into UDP datagrams, but this could
be provided by a separate ioctl(), and could default to the largest
message size that would fit in the MTU.

                                               -Bill

--
Johann Baudy
johaahn@gmail.com

--
Johann Baudy
johaahn@gmail.com