Re: [RFC PATCH] page_alloc: use first half of higher order chunks when halving

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, May 07, 2014 at 04:16:14PM -0700, Matthew Rushton wrote:
> On 04/16/14 07:15, Konrad Rzeszutek Wilk wrote:
> >On Mon, Apr 14, 2014 at 04:34:47PM +0100, Jan Beulich wrote:
> >>>>>On 14.04.14 at 16:40, <konrad.wilk@oracle.com> wrote:
> >>>That was OK, but the M2P lookup table was not too thrilled with this.
> >>>Perhaps I should have used another hypercall to re-arrange the M2P?
> >>>I think I did try 'XENMEM_exchange' but that is not the right call either.
> >>Yeah, that's allocating new pages in exchange for your old ones. Not
> >>really what you want.
> >>
> >>>Perhaps I should use XENMEM_remove_from_physmap/XENMEM_add_to_physmap
> >>>combo ?
> >>A pair of MMU_MACHPHYS_UPDATE operations would seem to be the
> >>right way of doing this (along with respective kernel internal accounting
> >>like set_phys_to_machine(), and perhaps a pair of update_va_mapping
> >>operations if the 1:1 map is already in place at that time, and you care
> >>about which page contents appears at which virtual address).
> >OK.
> >
> >Matt & Matthew - my plate is quite filled and I fear that in the next three
> >weeks there is not going to be much time to code up a prototype.
> >
> >Would either one of you be willing to take a crack at this? It would
> >be neat as we could remove a lot of the balloon increase/decrease code
> >in arch/x86/xen/setup.c.
> >
> >Thanks!
> 
> I have a first pass at this. Just need to test it and should have something
> ready sometime next week or so.

Woohoo! Thanks for the update!
> 
> >>Jan
> >>
>