Re: NUMA API for Linux

[Rajesh Venkatasubramanian <vrajesh@umich.edu>]

On Thu, 8 Apr 2004, Hugh Dickins wrote:

> On Thu, 8 Apr 2004, Rajesh Venkatasubramanian wrote:
> >
> > I guess using vm_private_data for nonlinear is not a problem because
> > we use list i_mmap_nonlinear for nonlinear vmas.
> >
> > As you have found out vm_private_data is only used if vm_file != NULL
> > or VM_RESERVED or VM_DONTEXPAND is set. I think we can revert back to
> > i_mmap{_shared} list for such special cases and use prio_tree for
> > others. I maybe missing something. Please teach me.
>
> Sorry, I don't understand what you're proposing here, and why?
> Oh, to save 4 bytes of vma by making the special cases use a list,
> no need for vm_set_head, and vm_private_data for the driver itself;
> but regular vmas use prio_tree, with vm_set_head in vm_private_data.

Yeah. You are right.

> Hmm, right now it's getting too much for me: can we keep it simplish
> for now, and come back to this later?

Yeah. This complicates the code further. That's why I didn't touch
it now. If things settle down and if we really worry about sizeof
vm_area_struct in the future, then we can remove the 8 bytes used
by prio_tree.

Rajesh