Re: Linux 2.6.17-rc2

[Jens Axboe <axboe@suse.de>]

On Thu, Apr 20 2006, David S. Miller wrote:
> From: Jens Axboe <axboe@suse.de>
> Date: Thu, 20 Apr 2006 21:34:31 +0200
> 
> > It should be able to, yes. Seems to me it should just work like regular
> > splicing, with the difference that you'd have to wait for the reference
> > count to drop before reusing. One way would be to do as Linus suggests
> > and make the vmsplice call block or just return -EAGAIN if we are not
> > ready yet. With that pollable, that should suffice?
> 
> Yes.
> 
> We really can't block on this, but I guess we could consider allowing
> that for really dumb applications.

It's up to the user, any non-dumb app would use SPLICE_F_NONBLOCK and
avoid blocking ofcourse.

> It does indeed require some smarts in the application to field the
> events, but by definition of using this splice stuff there is explicit
> knowledge in the application of what's going on.

Exactly.

> This is why I'm very hesitant to say "yeah, blocking on the socket is
> OK", because to be honest it's not.  As long as the socket buffer
> limits haven't been reached, we really shouldn't block so the user can
> go and do more work and create more transmit data in time to keep the
> network pipe full.

I'll post what I have tomorrow, lets take it from there.

-- 
Jens Axboe