Message-ID: <503BC298.3080306@redhat.com>
Date: Mon, 27 Aug 2012 11:55:20 -0700
From: Avi Kivity <avi@redhat.com>
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To: Michael Wolf <mjw@linux.vnet.ibm.com>
CC: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, peterz@infradead.org,
        mtosatti@redhat.com, glommer@parallels.com, mingo@redhat.com
Subject: Re: [PATCH RFC 0/3] Add guest cpu_entitlement reporting
References: <20120823231346.11681.1502.stgit@lambeau>
In-Reply-To: <20120823231346.11681.1502.stgit@lambeau>
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On 08/23/2012 04:14 PM, Michael Wolf wrote:
> This is an RFC regarding the reporting of stealtime.  In the case of
> where you have a system that is running with partial processors such as
> KVM the user may see steal time being reported in accounting tools such
> as top or vmstat.  This can cause confusion for the end user.  To
> ease the confusion this patch set adds a sysctl interface to set the
> cpu entitlement.  This is the percentage of cpu that the guest system is
>  expected to receive.  As long as the steal time is within its expected
> range it will show up as 0 in /proc/stat.  The user will then see in the
> accounting tools that they are getting a full utilization of the cpu
> resources assigned to them.
>
> This patchset is changing the contents/output of /proc/stat and could affect 
> user tools.  However the default setting is that the cpu is entitled to 100% 
> so the code will act as before.  Also another field could be added to the 
> /proc/stat output and show the unaltered steal time. Since this additional 
> field could cause more confusion than it would clear up I have left it out 
> for now.
>                 

How would a guest know what its entitlement is?


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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