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> The T2 instances use Hardware Virtualization (HVM) in order to get the best possible performance from the underlying CPU and you will need to use an HVM AMI.
by bowlofpetunias 12y ago
> The T2 instances use Hardware Virtualization (HVM) in order to get the best possible performance from the underlying CPU and you will need to use an HVM AMI.
I've always used paravirtual AMI's, as I understood that gets the best performance for a Linux box.
Given that I try to use the same self-baked base AMI's for various purposes (and instance sizes), I would either have to mix and match or switch everything to HVM. However, I have no clue what the practical consequences of that would be.
Can anybody enlighten me?
- helper 12y agoHVM vs PV is confusing because as Xen improves the performance characteristics of the two modes change. Brenden Gregg covered the differences in quite some detail in a recent blog post [1]. Basically, if you are running a new enough kernel on the guest os you will get better performance from HVM. [1]: http://www.brendangregg.com/blog/2014-05-07/what-color-is-your-xen.html http://www.brendangregg.com/blog/2014-05-07/what-color-is-yo...
- caw 12y agoHVM gives the best performance because you can take advantage of certain hardware features through the hypervisor. It's basically more direct access to the hardware, which makes it faster as you don't have as much hypervisor overhead. Amazon's "enhanced" networking and SSDs need HVM to get a good chunk of performance. Yes you'd have to build new AMIs with HVM. It'd be easiest if you had some kind of configuration management so you didn't need as many AMIs baked. When I build machines I use a script to handle the creation and mounting any extra volumes on a machine that I have as "nonstandard". I have only 2 custom AMIs - one for PV and the other for HVM. You'll need to have at least both, because if you wanted to use certain instances (t1.micro, m1.small come to mind) you can only use PV.