Native Linux KVM tool v2

Posted Jun 17, 2011 11:41 UTC (Fri) by Darkmere (subscriber, #53695)
In reply to: Native Linux KVM tool v2 by aliguori
Parent article: Native Linux KVM tool v2

Frankly, even when using virt-install I'm never certain if it's the right speed or not. Mostly _io_ tends to send systems into 20+ load "wait until world peace happens" even with (supposedly?) virtio enabled.

the current state of qemu-kvm is at times, a headache to deal with.

Speeding up qemu-kvm

Posted Jun 17, 2011 22:04 UTC (Fri) by jrn (subscriber, #64214) [Link]

Based on

> Some block drivers perform badly with cache=writethrough, most notably, qcow2. If performance is more important than correctness, cache=writeback should be used with qcow2.

I switched to cache=unsafe, and life became way better. The kind of tests I do in VMs let me recreate the image if there's a sudden crash, so safety is not such a worry. Not sure if virt-install does something like that.