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Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks
From: |
Michal Hocko |
Subject: |
Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks |
Date: |
Mon, 24 Jul 2017 11:00:43 +0200 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed 19-07-17 20:01:18, Wei Wang wrote:
> On 07/19/2017 04:13 PM, Michal Hocko wrote:
[...
> >All you should need is the check for the page reference count, no? I
> >assume you do some sort of pfn walk and so you should be able to get an
> >access to the struct page.
>
> Not necessarily - the guest struct page is not seen by the hypervisor. The
> hypervisor only gets those guest pfns which are hinted as unused. From the
> hypervisor (host) point of view, a guest physical address corresponds to a
> virtual address of a host process. So, once the hypervisor knows a guest
> physical page is unsued, it knows that the corresponding virtual memory of
> the process doesn't need to be transferred in the 1st round.
I am sorry, but I do not understand. Why cannot _guest_ simply check the
struct page ref count and send them to the hypervisor? Is there any
documentation which describes the workflow or code which would use your
new API?
--
Michal Hocko
SUSE Labs
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, (continued)
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michael S. Tsirkin, 2017/07/12
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/14
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michael S. Tsirkin, 2017/07/14
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/17
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/17
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/19
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/19
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks,
Michal Hocko <=
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wang, Wei W, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/25
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/26
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Wei Wang, 2017/07/26
- Re: [Qemu-devel] [PATCH v12 6/8] mm: support reporting free page blocks, Michal Hocko, 2017/07/26