Re: [kvm-devel] [RFC][PATCH 0/5] Memory merging driver for Linux

[Izik Eidus <izike@qumranet.com>]

Avi Kivity wrote:
> Chris Wright wrote:
>> * Izik Eidus (izike@qumranet.com) wrote:
>>  
>>> this module find this identical data (pages) and merge them into one 
>>> single page
>>> this new page is write protected so in any case the guest will try 
>>> to write to it do_wp_page will duplicate the page
>>>     
>>
>> What happens if you've merged more pages than you can recover on write
>> faults?
>>   
>
> You start to swap.  Just like Linux when you start to write on 
> fork()ed memory.
>
> A management application may start taking measures, like inflating 
> balloons and migrating to other hosts, but swapping is needed as a 
> last resort measure.
>
yes, write faults are getting into do_wp_page() that in turn create a 
new anonymous/swappable page
so it is safe.

-- 
woof.

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