linux-kernel - Re: [PATCH 03/11] Handle asynchronous page fault in a PV guest.

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Date:	Tue, 03 Nov 2009 16:38:46 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
CC:	Gleb Natapov <gleb@...hat.com>, kvm@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/11] Handle asynchronous page fault in a PV guest.

On 11/03/2009 04:32 PM, Marcelo Tosatti wrote:
> Any attempt to access the swapped out data will cause a #PF vmexit,
> since the translation is marked as not present. If there's swapin in
> progress, you wait for that swapin, otherwise start swapin and wait.
>
> Its not as efficient as paravirt because you have to wait for a timer
> interrupt and the guest scheduler to decide to taskswitch, but OTOH its
> transparent.
>    

With a dyntick guest the timer interrupt will come at the end of the 
time slice, likely after the page has been swapped in.  That leaves smp 
reschedule interrupts and non-dyntick guests.

An advantage is that there is one code path for apf and non-apf.  
Another is that interrupts are processed, improving timekeeping and 
maybe responsiveness.


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

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