Update: Debox sendfile modifications

[Igor Sysoev]

On Sun, 9 Nov 2003, John-Mark Gurney wrote:

> Igor Sysoev wrote this message on Sun, Nov 09, 2003 at 15:16 +0300:

> > > If you made this a fd transparent operation then I would agree with
> > > it.
> > 
> > The current sendfile() implementation works with sockets only.
> > Well, I agree that such sendfile() implementation is a hack.
> > Nowever this implementation is very usefull in the real world -
> > it allows to minimize a data copy in http and ftp servers.
> > 
> > I just could not figure to myself where can be usefull the
> > high perfomance sendfile() to a pipe.
> 
> It's not so much of how, but optimizing for the general case, not
> the specific case.  I was using pipes as an example, what about for
> coping one fd to another?  Right now cp will try to mmap a 16meg buffer,
> and use that, if it fails, it falls back to a read/write loop.. why
> not do something like copyfd that does it more optimally?
> 
> > I think that it's better to leave sendfile() as a sending to a socket
> > only hack. I believe that any sendfile() generalization (e.g. sending
> > data from a socket to a file) is useless.
> 
> oh? why do you think that is useless?  What about all the applications
> like ftp clients, and wget/fetch/curl that do it on a regular basis?

To notice some perfomance impact of using sendfile() in cp, wget, etc
I need to run simultaneously hundreds of these applications.
To see the perfomance impact of using sendfile() in http or ftp server
I need to serve hundreds of clients. The first case is too rare
while the second one is common for the busy servers.


Igor Sysoev
http://sysoev.ru/en/