linux-kernel - Re: [PATCH 0/4] Alter steal-time reporting in the guest

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Message-ID: <CAFTL4hx8ibTVQpObiEpribKZNhYSpwm05dOf9-CGX7YiVdC2qg@mail.gmail.com>
Date:	Wed, 6 Mar 2013 14:20:36 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
Cc:	Michael Wolf <mjw@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, riel@...hat.com, gleb@...hat.com,
	kvm@...r.kernel.org, peterz@...radead.org, glommer@...allels.com,
	mingo@...hat.com, anthony@...emonkey.ws
Subject: Re: [PATCH 0/4] Alter steal-time reporting in the guest

2013/2/19 Marcelo Tosatti <mtosatti@...hat.com>:
> On Mon, Feb 18, 2013 at 05:43:47PM +0100, Frederic Weisbecker wrote:
>> 2013/2/5 Michael Wolf <mjw@...ux.vnet.ibm.com>:
>> > In the case of where you have a system that is running in a
>> > capped or overcommitted environment the user may see steal time
>> > being reported in accounting tools such as top or vmstat.  This can
>> > cause confusion for the end user.
>>
>> Sorry, I'm no expert in this area. But I don't really understand what
>> is confusing for the end user here.
>
> I suppose that what is wanted is to subtract stolen time due to 'known
> reasons' from steal time reporting. 'Known reasons' being, for example,
> hard caps. So a vcpu executing instructions with no halt, but limited to
> 80% of available bandwidth, would not have 20% of stolen time reported.

Ok, that's a good explanation to add to make that subtle steal time
issue clearer.

>
> But yes, a description of the scenario that is being dealt with, with
> details, is important.

Yeah especially for such a significant user ABI change.
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