> -----Original Message----- > From: IBM Mainframe Assembler List [mailto:ASSEMBLER- > [email protected]] On Behalf Of glen herrmannsfeldt > Sent: 25 March 2015 16:53 > To: [email protected] > Subject: Intel Virtualization > > > As for the ISA, Intel seems to be very "ad hoc" compared to the z > > architecture. Especially in the virtualization arena. Basically, the z > > has a _single_ virtualization instruction: SIE. > > Intel has I don't know how many different versions of different > > instructions to let hypervisors run at all. I don't know how efficient > > vitualization actually is on Intel. > > But it wouldn't surprise me if it were a pig. > > As far as I know, the biggest advantage z/ has over Intel (and many others) is > the wait state. > > It is sometimes difficult for virtualization to figure out when the guest isn't > doing anything. Most other systems use a null process with a small loop, > while waiting for an interrupt. > (But if you know you are running virtual, there might be some way around it.) >
Largely fixed in later Linux, Solaris and Windows kernels (Post Windows/2000, so basically Windows2003 or newer, Solaris 9 or newer, say 12 or 13 years old... > I beleive that the wait state came from the days of usage meters, when the > meter would stop while the processor was waiting. If not for rentals of > S/360, it might not have had the wait state. > > -- glen > >
