Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Kamezawa Hiroyuki wrote:
> Ingo Molnar wrote:
>
> > so it's all about expectations: _could_ you reasonably remove a piece 
> > of RAM? Customer will say: "I have stopped all nonessential services, 
> > and free RAM is at 90%, still I cannot remove that piece of faulty 
> > RAM, fix the kernel!". No reasonable customer will say: "True, I have 
> > all RAM used up in mlock()ed sections, but i want to remove some RAM 
> > nevertheless".
> Hi, I'm one of men in -lhms
>
> In my understanding...
> - Memory Hotremove on IBM's LPAR? approach is
>   [remove some amount of memory from somewhere.]
>   For this approach, Mel's patch will work well.
>   But this will not guaranntee a user can remove specified range of
>   memory at any time because how memory range is used is not defined by 
> an admin
>   but by the kernel automatically. But to extract some amount of memory,
>   Mel's patch is very important and they need this.
One more consideration...
Some cpus which support virtialization will be shipped by some vendor in near future.
If someone uses vitualized OS, only problem is *resizing*.
Hypervisor will be able to remap semi-physical pages anyware with hardware assistance
but system resizing needs operating system assistance.
To this direction, [remove some amount of memory from somewhere.] is important approach.

-- Kame


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