Re: [Xen-devel] Error restoring DomU when using GPLPV

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Yeah, all the PV drivers are having to do is balloon down one page for every
Xenheap page they map. There's no further complexity than that, so let's not
make a mountain out of a molehill. The approach as discussed and now
implemented should work fine with tmem I think.

 -- Keir

On 16/09/2009 21:50, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:

> just in case someone missed the thread earlier,
> 
> 3 = 1 shinfo + 2 gnt frames default.
> 
> so, tot_pages + shinfo + num gnt frames.
> 
> 
> Mukesh
> 
> 
> 
> Dan Magenheimer wrote:
>> Before we close down this thread, I have a concern:
>> 
>> According to Mukesh, the fix to this bug is dependent
>> on the pv drivers tracking tot_pages for a domain
>> and ballooning to ensure tot_pages+3 does not exceed
>> max_pages for the domain.
>> 
>> Well, tmem can affect tot_pages for a domain inside
>> the hypervisor without any notification to pv drivers
>> or the balloon driver.  And I'd imagine that PoD and
>> future memory optimization mechanisms such as
>> swapping and page-sharing may do the same.
>> 
>> So this solution seems very fragile.
>> 
>> Dan
>> 
>>> -----Original Message-----
>>> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
>>> Sent: Wednesday, September 16, 2009 6:28 AM
>>> To: Annie Li
>>> Cc: Joshua West; Dan Magenheimer; xen-devel; Kurt Hackel;
>>> James Harper;
>>> Wayne Gong
>>> Subject: Re: [Xen-devel] Error restoring DomU when using GPLPV
>>> 
>>> 
>>> On 16/09/2009 12:10, "ANNIE LI" <annie.li@xxxxxxxxxx> wrote:
>>> 
>>>>> I will do more test to make sure it and update here.
>>>> I tried to map 256 grant frames during initialization and
>>> balloon down
>>>> 256+1(shinfo+gnttab) pages driver first
>>>> load. Then i did save/restore for 50 times, and live
>>> migration for 10
>>>> times. No error occurs.
>>> Okay, well I still can't explain why that fixes it, but
>>> clearly it does. So
>>> that's good. :-)
>>> 
>>>  -- Keir
>>> 
>>> 
>>> 
>> 
>> _______________________________________________
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>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel



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