On Mon, Feb 18, 2019 at 8:07 PM Joe Duarte <[email protected]> wrote:
> Thanks Pekka, I'll check it out. > Good. I think this will clear some of the misconceptions you may have. > One of the advantages of KVM is supposed to be that it uses the Linux > kernel scheduler instead of having two schedulers, such as Xen's scheduler > + a VM's or unikernel's scheduler. I'll see what the paper has to say about > that. > 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. OSv is a an operating system for *one* virtual machine. This virtual machine may have several virtual CPUs, and may (and usually does) want to run many threads on them, and for that OSv needs a scheduler for those threads, to decide which of the threads runs on which virtual CPU, and when. OSv does support threads, as almost any modern application needs them, and they are absolutely needed if you have multiple virtual CPUs in one VM (you cannot run just one thread on multiple CPUs). What OSv does not support are old-school "processes", which are threads which are isolated from each other - each having a different address space, and often running a different application. This sort of isolation comes at a cost, which OSv wanted to avoid. This is explained in detail in the paper. > JD > > On Sunday, February 17, 2019 at 10:28:26 PM UTC-8, Pekka Enberg wrote: >> >> Hello, >> >> On Sun, Feb 17, 2019 at 11:45 PM Joe Duarte <[email protected]> wrote: >> >>> Hi all -- Does OSv have its own scheduler, or does it rely on the Xen >>> scheduler? >>> >>> I guess this might be similar to asking if OSv has threads. I have no >>> idea. I'm not sure what being a unikernel is supposed to imply for threads. >>> >> >> OSv indeed has as a scheduler to support threads. You can find a more >> detailed discussion in the OSv paper, for example: >> >> >> https://www.usenix.org/system/files/conference/atc14/atc14-paper-kivity.pdf >> >> - Pekka >> > -- > 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. > -- 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.
