Re: [Qemu-devel] Virtual memory question

[Dennis <dennis@satanclaus.com>]

On Mon, Aug 9, 2010 at 9:41 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> On Mon, Aug 9, 2010 at 7:49 PM, Dennis <dennis@satanclaus.com> wrote:
>> I have an application that takes up over 2 GB of memory but is
>> otherwise demanding virtually no other resources at all.
>> Running multiple instances of the application using physical memory
>> isn't an option. Would it be hard to change Qemu's
>> physical memory mapping to a file on disk ? (Not Qemu-KVM, just stock Qemu).
>
> It's not 100% clear what you are trying to do, but are you aware that
> guest "physical" memory can be swapped on the host?

I know, but the host machine would have to run out of memory before it swaps.
That's not very desirable ;-)

> Also, have you looked at Kernel Samepage Merging (KSM)?  KSM detects
> guest physical pages that contain the same contents and merge them
> into a single page, saving memory.  This is appropriate if you run
> multiple VMs based off the same disk image and expect they will be
> executing the same code.  For more info, see
> http://kernelnewbies.org/Linux_2_6_32#head-d3f32e41df508090810388a57efce73f52660ccb.

I havn't yet. One "problem" is I _have_ to run Qemu on FreeBSD. I
doubt it's possible.