Messages in this thread | | | Date | Wed, 2 Nov 2005 11:41:31 +0100 | From | Ingo Molnar <> | Subject | Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 |
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* Gerrit Huizenga <gh@us.ibm.com> wrote:
> > generic unpluggable kernel RAM _will not work_. > > Actually, it will. Well, depending on terminology.
'generic unpluggable kernel RAM' means what it says: any RAM seen by the kernel can be unplugged, always. (as long as the unplug request is reasonable and there is enough free space to migrate in-use pages to).
> There are two usage models here - those which intend to remove > physical elements and those where the kernel returnss management of > its virtualized "physical" memory to a hypervisor. In the latter > case, a hypervisor already maintains a virtual map of the memory and > the OS needs to release virtualized "physical" memory. I think you > are referring to RAM here as the physical component; however these > same defrag patches help where a hypervisor is maintaining the real > physical memory below the operating system and the OS is managing a > virtualized "physical" memory.
reliable unmapping of "generic kernel RAM" is not possible even in a virtualized environment. Think of the 'live pointers' problem i outlined in an earlier mail in this thread today.
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