[uml-devel] Re: V=R

[Michael Koehne <kraehe@copyleft.de>]

Moin Jeff Dike,

> On Sat, Apr 10, 2004 at 01:06:51PM +0200, Sven Köhler wrote:
> > is there any way for the UML-kernel to allocate a non-swappable 
> > memore-region in the host's memory? this could be especially important 
> > for dedicated host-machines that are only to run UMLs.
> 
> What I am going to do is make it possible to manage the host's memory
> so that it doesn't swap, and the UMLs in effect are mlocked.

  this reminds me on VM's V=R nucleus option. A V=R is a memory partition
  dedicated to 1 user, e.g. an MVS guest running under VM who is doing its
  own demand paging. To translate this to Linux could be the following :

  e.g. a system with 1GB real ram could boot `linux mem=256m` with
  only a quarter of ram for the hosting system. We now need two tricks:

  1: add 768m of ram as V=R memory (dont use it for Linux processes,
     buffers, ...) partition and offer it as /dev/v=r. (this would
     be a host kernel patch)

  2: use this V=R region for UML `linux mem=256m@256m` (this would
     be a user kernel patch)

  I dont know how difficult implementation would be, but I think most
  of an UML V=R is already there. The real V=R is vice versa, so VM
  is running in upper core, to offer the lower core to the one and
  only guest a virtual=real environment.

Bye Michael
-- 
  mailto:kraehe@copyleft.de             UNA:+.? 'CED+2+:::Linux:2.4.22'UNZ+1'
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