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Re: [Xen-users] Linux CONFIG_HZ_100=y or CONFIG_HZ_1000=y for Xen dom0/d

To: "Martinx - ?$B%8%'!<%`%:" <thiagocmartinsc@xxxxxxxxx>
Subject: Re: [Xen-users] Linux CONFIG_HZ_100=y or CONFIG_HZ_1000=y for Xen dom0/domUs?
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Thu, 18 Mar 2010 21:23:44 +0200
Cc: Xen List <xen-users@xxxxxxxxxxxxxxxxxxx>
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On Wed, Mar 17, 2010 at 02:10:11PM -0300, Martinx - ?$B%8%'!<%`%: wrote:
>    Hi!
> 
>     The kernel shipped by Citrix for Debian via xen-tools are configured with
>    CONFIG_HZ_100=y, but the Debian kernels and my custom kernels are
>    configured for CONFIG_HZ_250=y or even CONFIG_HZ_1000=y.
> 
>     So, what is the impact of this clock to a Xen system?
> 
>     Which option is more suitable for Xen systems?
> 

This is really common for all virtualized environments, so it also applies
to VMware etc.

Your _guest_ kernel should have HZ=100 rather than HZ=1000. HZ=100 will use 
a lot less CPU time when the guest is idle.

-- Pasi


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