Re: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> 
> 
> On 04/03/2016 15:26, Li, Liang Z wrote:
> >> > 
> >> > The memory usage will keep increasing due to ever growing caches, etc, so
> >> > you'll be left with very little free memory fairly soon.
> >> > 
> > I don't think so.
> > 
> 
> Roman is right.  For example, here I am looking at a 64 GB (physical)
> machine which was booted about 30 minutes ago, and which is running
> disk-heavy workloads (installing VMs).
> 
> Since I have started writing this email (2 minutes?), the amount of free
> memory has already gone down from 37 GB to 33 GB.  I expect that by the
> time I have finished running the workload, in two hours, it will not
> have any free memory.

But what about a VM sitting idle, or that just has more RAM assigned to it
than is currently using.
 I've got a host here that's been up for 46 days and has been doing some
heavy VM debugging a few days ago, but today:

# free -m
              total        used        free      shared  buff/cache   available
Mem:          96536        1146       44834         184       50555       94735

I very rarely use all it's RAM, so it's got a big chunk of free RAM, and yes
it's got a big chunk of cache as well.

Dave

> 
> Paolo
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK