Re: Slow VM start/revert, when trying to start/revert dozens of VMs in parallel

Hi, my problem can be described simply: libvirt can't handle starting dozens of VMs at the same time. (technically, it can, but it's really slow.) We have an AMD machine with 256 logical cores and 1.5T ram. On that machine there is roughly 200 VMs. Each VM is the same: 8GB of RAM, 4 VCPUs. Half of them is Win7 x86, the other half is Win7 x64. VMs are using qcow2 as the disk image. These images reside in the ramdisk (tmpfs). We use these machines for automatic malware analysis, so our scenario consists of this cycle: - reverting VM to a running state - execute sample inside of the VM for ~1-2 minutes - shutdown the VM Of course, this results in multiple VMs trying to start at the same time. At first, reverts/starts are really fast - second or two. After about a minute, the "revertToSnapshot" suddenly takes 10-15 seconds, which is really unacceptable. For comparison, we're running the same scenarion on Proxmox, where the revertToSnapshot usually takes 2 seconds.