linux-kernel - Re: [RFC][PATCH v2 4/7] taskstats: Add per task steal time accounting

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Date:	Tue, 16 Nov 2010 19:06:55 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Michael Holzheu <holzheu@...ux.vnet.ibm.com>,
	Shailabh Nagar <nagar1234@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Oleg Nesterov <oleg@...hat.com>,
	John stultz <johnstul@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	"jeremy.fitzhardinge" <jeremy.fitzhardinge@...rix.com>
Subject: Re: [RFC][PATCH v2 4/7] taskstats: Add per task steal time accounting

On 11/16/2010 06:56 PM, Avi Kivity wrote:
> On 11/16/2010 06:43 PM, Peter Zijlstra wrote:
>>
>>> No.  Hypercalls are voluntary and known, but most exits are involuntary
>>> and unknown to the guest.  Any memory access can generate a page fault,
>>> and any host interrupt will exit the guest.
>> Right, but we could not make the guest jump to a special stub on vcpu
>> enter? I guess we could simply because we have the hypervisor under
>> control.
>
> No, some entries inject an interrupt or exception, so the next rip 
> value is unknown (without doing a lot of extra slow calculations).

Also, consider an exit within the stub (if the stub is paged out, for 
example).

-- 
error compiling committee.c: too many arguments to function

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