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

[Matthew Rushton <mvrushton@gmail.com>]

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!

Yeah sure. It won't be immediatly but I should be able to do that.


>> Jan
>>