linux-kernel - Re: [PATCH 4/4] Add a timer to allow the separation of consigned from steal time.

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Date:	Wed, 06 Feb 2013 12:07:38 -0600
From:	Michael Wolf <mjw@...ux.vnet.ibm.com>
To:	Glauber Costa <glommer@...allels.com>
CC:	linux-kernel@...r.kernel.org, riel@...hat.com, gleb@...hat.com,
	kvm@...r.kernel.org, peterz@...radead.org, mtosatti@...hat.com,
	mingo@...hat.com, anthony@...emonkey.ws
Subject: Re: [PATCH 4/4] Add a timer to allow the separation of consigned
 from steal time.

On 02/06/2013 08:36 AM, Glauber Costa wrote:
> On 02/06/2013 01:49 AM, Michael Wolf wrote:
>> Add a helper routine to scheduler/core.c to allow the kvm module
>> to retrieve the cpu hardlimit settings.  The values will be used
>> to set up a timer that is used to separate the consigned from the
>> steal time.
> Sorry: What is the business of a timer in here?
> Whenever we read steal time, we know how much time has passed and with
> that information we can know the entitlement for the period. This breaks
> if we suspend, but we know that we suspended, so this is not a problem.
I may be missing something, but how do we know how much time has 
passed?  That is why
I had the timer in there.  I will go look again at the code but I 
thought the data was collected
as ticks and passed at random times.  The ticks are also accumulating so 
we are looking at the
difference in the count between reads.....

>
> Everything bigger the entitlement is steal time.
I agree provided I know the amount of total time that the steal time was 
accumulated.
>
>
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