On Monday, February 18, 2019 at 1:43:29 PM UTC-8, Nadav Har'El wrote: > > > > KVM and Xen are *hypervisors*, i.e., software which allows running > multiple virtual-machines on one physical machine. > The "Linux scheduler" and "Xen scheduler" you mention are implementation > details of that hypervisor, and has nothing to do with OSv. > > Right, I know all that. What I was saying is that KVM is supposed to have an *advantage* over Xen because there's only one scheduler, because while KVM is technically a hypervisor, it's in the Linux kernel (not underneath it like Xen). I got this point from Brendan Gregg, a performance engineer at Joyent and now Netflix. One place he touches on it is in this doc <http://www.brendangregg.com/Articles/Virtualization_Performance_Zones_KVM_Xen.pdf>: "With KVM, the hypervisor is a kernel module (kvm) which is scheduled by the OS scheduler. It can be tuned using the usual OS kernel scheduler classes, policies and priorities. The I/O path takes fewer steps than Xen."
I took this as having implications for OSv since OSv also runs on top of Xen with, apparently, its own scheduler. (I don't know if it's restricted to Xen anymore.) I don't know if or how the schedulers interact. Is OSv I/O (on Xen) faster than KVM VM I/O? Table 1 from the paper might bear on it, but it's five years old and I'm not clear as to what the Linux setup was (was it Fedora 20 running KVM with a Fedora 20 guest on top?). JD -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
