Re: [PATCH] VMware Balloon driver

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 04/06/2010 11:36 AM, Avi Kivity wrote:
> On 04/06/2010 09:25 PM, Jeremy Fitzhardinge wrote:
>> On 04/06/2010 09:32 AM, Avi Kivity wrote:
>>> Yeah.  If we wanted commonality, we could make a balloon_core.c that 
>>> contains the common code.  IMO that's premature, but perhaps there's 
>>> some meat there (like suspend/resume support and /proc//sys interface).
>>
>> I think it would be useful to have common:
>>
>>   1. User and kernel mode ABIs for controlling ballooning.  It assumes
>>      that the different balloon implementations are sufficiently
>>      similar in semantics.   (Once there's a kernel ABI, adding a
>>      common user ABI is trivial.)
>>   2. Policy driving the ballooning driver, at least from the guest
>>      side.  That is, some good metrics from the vm subsystem about
>>      memory pressure (both positive and negative), and something to
>>      turn those metrics into requests to the balloon driver.
>>
>> 1) is not a huge amount of code, but something consistent would be 
>> nice.  2) is something we've been missing and is a bit of an open 
>> question/research project anyway.
>
> 3) Code that attempts to reclaim 2MB pages when possible

Yes.  Ballooning in 4k units is a bit silly.

     J