Re: [Qemu-devel] [Bug]? (RDMA-related) ballooned memory not consulted during migration?

[Michael R. Hines]

Actually, you don't even need ballooning to reproduce this behavior.

Is this a known issue?

- Michael


On 03/19/2013 11:02 AM, Michael R. Hines wrote:
> Consider the following sequence:
>
> 1. Boot fresh VM (say, a boring 1GB vm)                    => Resident 
> set is small, say 100M
> 2. Touch all the memory (with a utility or something) => Resident set 
> is ~1G
> 3. Send QMP "balloon 500" => Resident set is ~500M
> 4. Now, migrate the VM => Resident set is 1G again
>
> This suggests to me that migration is not accounting for
> what memory was ballooned.
>
> I suspect this is because the migration_bitmap does not coordinate
> with the list of ballooned-out memory that was MADVISED().
>
> This affects RDMA as well as TCP on the sender side.
>
> Is there any hard reason why we're not validating migration_bitmap 
> against
> the memory that was MADVISED()'d?
>
> - Michael R. Hines