Uwe Klein wrote: > David Woolley wrote: >> Evandro Menezes wrote: >> >> HLT instructions are a complete red herring here. They've been available > Modern CPUs, chipsets and OSes have a wide range of features to manage
I'm aware of that. > power _and_ these are heavily used on any platform, be it PDA, Laptop, > embedded > device .. or Numbercrunching Cluster. My argument is that these aren't or shouldn't be important for servers. > The current trend seems to be dedicated boxes > or myriads of "VM-boxes" on a mainframe which depends heavily > on a VM-box being suspended when it is idle. That only requires the 1970s (or earlier) HLT technology and multi-tasking friendly applications; generally Unix applications are friendly but some Windows applications, particularly from five or more years ago, aren't (although they tend to be desk top ones). > I haven't looked into how the VM people handle timekeeping though. A typical solution is to run ntpd on the host system and run some code that is virtualisation aware and can peek at the host system, to, in some proprietary way, align the virtual software clock with the host software clock. Trying to run time synchronisation directly on the guest is a recipe for disaster. One impact of virtualisation is that the virtual machines cannot coordinate their timer interrupts unless they include extensive virtualisation aware code. My impression is that the VMWare code doesn't go anything like that far. Also, as I understand it, enterprise (i.e. expensive) virtualisation software can move running guests between hosts, so, whilst that would be rather bad for timing critical applications, one imagines the best power management strategy is to concentrate the active systems on a few hosts and completely power down any others. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
