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Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend r
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields |
Date: |
Wed, 26 Feb 2014 09:58:14 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Feb 26, 2014 at 01:45:38PM +0100, Paolo Bonzini wrote:
> Il 26/02/2014 13:31, Igor Mammedov ha scritto:
> >>> The problem is that some backends might not be handled the same way.
> >>> For example, not all backends might produce a single void*/size_t pair
> >>> for the entire region. Think of a "composite" backend that produces a
> >>> large memory region from two smaller ones.
> >I'd prefer to keep backends simple, with 1:1 mapping to memory regions.
>
> I agree. However not all backends may have a mapping to a RAM
> memory region. A composite backend could create a container memory
> region whose children are other HostMemoryBackend objects.
>
> >Is there a need in composite one or something similar?
>
> I've heard of users that want a node backed partially by hugetlbfs
> and partially by regular RAM. Not sure why.
>
> Paolo
To overcommit the non hugetlbfs backed guest RAM (think guest pagecache on that
non
hugetlbfs backed memory, swappable and KSM-able).
The problem is, you have to in someway guarantee the guest allocates
1GB pages out of the hugetlb backed GPA ranges. Some thoughts
(honestly, dislike all of them):
1) Boot guest with hugepages, allocate hugepages in guest,
later on hotplug 4K backed ranges. HV-unaware reboot might fail,
though.
2) Communicate hugepage GPAs to guest.
3) Create holes in non hugepage backed GPA range.
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, (continued)
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Hu Tao, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Igor Mammedov, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Igor Mammedov, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields,
Marcelo Tosatti <=
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Igor Mammedov, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Igor Mammedov, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Paolo Bonzini, 2014/02/26
- Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields, Hu Tao, 2014/02/25
[Qemu-devel] [PATCH v18 12/14] qapi: add HostMemPolicy enum type, Hu Tao, 2014/02/19