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Re: [Xen-devel] Poor HVM performance with 8 vcpus

  • To: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
  • Date: Wed, 07 Oct 2009 10:31:05 +0200
  • Cc: James Harper <james.harper@xxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Wed, 07 Oct 2009 01:31:32 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Ian Pratt wrote:
>> Are there any other of these heuristics tucked away in xen? Would there
>> be any benefit to specifying the OS being virtualised in the config? Eg
>> "os=windows"?
> That's really the only one that springs to mind.
> Given how simple a predictor would be, I think that's the best approach.
> Setting the OS in the config file is a little tricky as in a couple of 
> instances you'd want to know the exact version (linux moved the 64b direct 
> mapped region at some point during 2.6 development).

I think it is a bad idea in most cases to use such a basic parameter like
"os=xyz" to tune some specific behaviour. It may be useful to set some default
parameters, but there should be an explicit parameter as well, e.g.


Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 636 47950
Fujitsu Technolgy Solutions               e-mail: juergen.gross@xxxxxxxxxxxxxx
Otto-Hahn-Ring 6                        Internet: ts.fujitsu.com
D-81739 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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