Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool

[Anthony Liguori]

Gerd Hoffmann wrote:
> > > To solve this in userland without kernel aio we'd need to open (not
> > > just dup)
> > >       
> > Why not just dup?  I've implemented this and it seems to work.
> >     
>
> unix keeps the file pointer in the (global) file table.  The
> (per-process) file descriptor table references the file table.
>
> opening twice gives you two file descriptor table entries referencing
> two file table entries.  duping gives you two file descriptors
> referencing the *same* file table entry.  Thus the two fds share the
> file pointer.
>   

But opening twice means that you lose coherency with NFS.

I hate Unix.

Regards,

Anthony Liguori

> HTH,
>   Gerd
>
>
>