Re: Status of AIO

[Dan Aloni <da-x@monatomic.org>]

On Mon, Mar 06, 2006 at 09:07:36PM -0500, Benjamin LaHaise wrote:
> On Tue, Mar 07, 2006 at 04:04:11AM +0200, Dan Aloni wrote:
> > This somehow resembles the scatter-gatter lists already used in some 
> > subsystems such as the SCSI sg driver. 
> 
> None of the iovecs are particularly special.  What's special here is that 
> particulars of the container make the fast path *cheap*.
> 
> > BTW you have to make these pages Copy-On-Write before this procedure 
> > starts because you wouldn't want it to accidently fill the zero page, 
> > i.e. the VM will have to supply a unique set of pages otherwise it 
> > messes up.
> 
> No, that would be insanely expensive.  There's no way this would be done 
> transparently to the user unless we know that we're blocking until the 
> transmit is complete.

Sure it can't be transparent to the user, but you can just require the user 
to perform mlock on the VMA and you get around this problem.

-- 
Dan Aloni
da-x@monatomic.org, da-x@colinux.org, da-x@gmx.net, dan@xiv.co.il