2007/10/15, Gerd Hoffmann <[EMAIL PROTECTED]>: > Avi Kivity wrote: > > Gerd Hoffmann wrote: > >> > >>> 2) the TSC would have to be used as a clocksource. You don't know the > >>> frequency which is the first problem with using the TSC but some systems > >>> have a TSC that changes frequencies. > >>> > >> Also note the tsc may stop ticking if the CPU goes sleep in C3, which > >> IMHO makes the tsc almost useless as clocksource for guests ... > > > > But the host knows that, right? So it can update the guest's timebase? > > Host should know. Well, I hope. Dunno whenever one really can be sure > in all cases given all the different CPUs and tsc implementations. > > With VT you can attempt to make that invisible to the guest using the > tsc offset field. Probably svm can do that too (didn't check docs > though). kvm-lite can't (what is the status btw?). Xen "solves" that > by not doing power management *evil grin*. > > Nevertheless it is probably much easier to go with pv timers (or maybe > emulate hpet timers). > > cheers, > Gerd
Hell I don't know what is the best technical way to solve this problem, but as a sysadmin, I'm really "annoyed" when the time starts to drift madly on the servers as soon as the host is loaded (talking about esx servers there but I guess this will probably apply to any existing x86 virtualisation solution). A simple, reliable solution to get a stable time source is not a must IMHO, it is a usability requirement. Cheers, Gildas ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
