On 21.07.20 17:27, Julien Grall wrote:
Hi,
Hello
On a similar topic, I am a bit surprised you didn't encounter memory
exhaustion when trying to use virtio. Because on how Linux currently
works (see XSA-300), the backend domain as to have a least as much RAM
as the domain it serves. For instance, you have serve two domains with
1GB of RAM each, then your backend would need at least 2GB + some for
its own purpose.
This probably wants to be resolved by allowing foreign mapping to be
"paging" out as you would for memory assigned to a userspace.
Didn't notice the last sentence initially. Could you please explain your
idea in detail if possible. Does it mean if implemented it would be
feasible to map all guest memory regardless of how much memory the guest
has? Avoiding map/unmap memory each guest request would allow us to have
better performance (of course with taking care of the fact that guest
memory layout could be changed)... Actually what I understand looking at
kvmtool is the fact it does not map/unmap memory dynamically, just
calculate virt addresses according to the gfn provided.
--
Regards,
Oleksandr Tyshchenko