I would think that the problem is that OpenStack does not really report back that you are using KVM - it reports that you are using QEMU.
Even when in nova.conf I have configured virt_type=kvm, when I run nova hypervisor-show XXX | grep hypervisor_type I am presented with the following | hypervisor_type | QEMU Bug? On 03/05/16 18:01, Daniel P. Berrange wrote: > Hello Operators, > > One of the things that constantly puzzles me when reading the user > survey results wrt hypervisor is the high number of respondants > claiming to be using QEMU (as distinct from KVM). > > As a reminder, in Nova saying virt_type=qemu causes Nova to use > plain QEMU with pure CPU emulation which is many many times slower > to than native CPU performance, while virt_type=kvm causes Nova to > use QEMU with KVM hardware CPU acceleration which is close to native > performance. > > IOW, virt_type=qemu is not something you'd ever really want to use > unless you had no other options due to the terrible performance it > would show. The only reasons to use QEMU are if you need non-native > architecture support (ie running arm/ppc on x86_64 host), or if you > can't do KVM due to hardware restrictions (ie ancient hardware, or > running compute hosts inside virtual machines) > > Despite this, in the 2016 survey 10% claimed to be using QEMU in > production & 3% in PoC and dev, in 2014 it was even higher at 15% > in prod & 12% in PoC and 28% in dev. > > Personally my gut feeling says that QEMU usage ought to be in very > low single figures, so I'm curious as to the apparent anomoly. > > I can think of a few reasons > > 1. Respondants are confused as to the difference between QEMU > and KVM, so are saying QEMU, despite fact they are using KVM. > > 2. Respondants are confused as to the difference between QEMU > and KVM, so have mistakenly configured their nova hosts to > use QEMU instead of KVM and suffering poor performance without > realizing their mistake. > > 3. There are more people than I expect who are running their > cloud compute hosts inside virtual machines, and thus are > unable to use KVM. > > 4. There are more people than I expect who are providing cloud > hosting for non-native architectures. eg ability to run an > arm7/ppc guest image on an x86_64 host and so genuinely must > use QEMU > > If items 1 / 2 are the cause, then by implication the user survey > is likely under-reporting the (already huge) scale of the KVM usage. > > I can see 3. being a likely explanation for high usage of QEMU in a > dev or PoC scenario, but it feels unlikely for a production deployment. > > While 4 is technically possible, Nova doesn't really do a very good > job at mixed guest arch hosting - I'm pretty sure there are broken > pieces waiting to bite people who try it. > > Does anyone have any thoughts on this topic ? > > Indeed, is there anyone here who genuinely use virt_type=qemu in a > production deployment of OpenStack who might have other reasons that > I've missed ? > > Regards, > Daniel -- Best Regards, Maish Saidel-Keesing
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