On 14.02.19 10:12, Wang, Wei W wrote: > On Thursday, February 14, 2019 1:22 AM, Nitesh Narayan Lal wrote: >> In normal condition yes we would not like to report any memory when the >> guest is already under memory pressure. >> >> I am not sure about the scenario where both guest and the host are under >> memory pressure, who will be given priority? Is it something per-decided or >> it depends on the use case? >> > > That's one of the reasons that I would vote for "host to ask for free pages". As I already said, there are scenarios where this does not work reliably. When we 1. Let the guest report free pages 2. Allow the hypervisor to enable/disable it We have a mechanism that is superior to what you describe. "host to ask for free pages" can be emulated using that. > > Host can have a global view of all the guest's memory states, so better to have the > memory overcommitment policy defined on the host. > > For example, the host can know guest1 is under memory pressure (thus not asking him) > and guest2 has a huge amount of free memory. When host lacks memory to run the 3rd > guest, it can asks guest2 to offer some free memory. > > Best, > Wei > -- Thanks, David / dhildenb
