Re: [PATCH 2/2] kvm: change the dirty page tracking to work with dirty bity

[Izik Eidus <ieidus@redhat.com>]

Avi Kivity wrote:
> Izik Eidus wrote:
>> change the dirty page tracking to work with dirty bity instead of 
>> page fault.
>> right now the dirty page tracking work with the help of page faults, 
>> when we
>> want to track a page for being dirty, we write protect it and we mark 
>> it dirty
>> when we have write page fault, this code move into looking at the 
>> dirty bit
>> of the spte.
>>
>>   
>
> I'm concerned about performance during the later stages of live 
> migration.  Even if only 1000 pages are dirty, you still have to look 
> at 2,000,000 or more ptes (for an 8GB guest).  That's a lot of overhead.
>
> I think we need to use the page table hierarchy, write protect the 
> upper page table so we know which page tables we need to look at.
>
>

Great idea, so i add another bitmap for the page directory?
>>  
>> +static int vmx_dirty_bit_support(void)
>> +{
>> +    return false;
>> +}
>>   
>
> It's false only when ept is enabled.
>

Yea, that i found out already....