[Qemu-devel] slow migration speed / strange memory usage

[Stefan Priebe - Profihost AG]

Hello list,

i'm running kvm 1.2 on vanilla 3.6.3 kernel.

I'm trying to understand the memory usage and the migration speed.

I've a VM which does nothing else than running OpenSSH and a cron job 
every minute to write a small json file.

When the VM is freshly started Host shows 300MB memory usage and 
migration speed is around 400MB/s.

After time the memory usage increases in up to 3.7GB but in VM it stays 
incl. cache and buffers around 350MB.

The migration speed is then around 25MB/s.

How can this be? Is this expected? Disk cache is set to default (no cache).

Greets,
Stefan