On Mon, Dec 11, 2017 at 06:14:54PM +0100, Andrea Bolognani wrote: > On Mon, 2017-12-11 at 16:46 +0000, Daniel P. Berrange wrote: > > On Mon, Dec 11, 2017 at 05:40:36PM +0100, Andrea Bolognani wrote: > > > Some ARM platforms, such as the original Raspberry Pi, report the > > > CPU frequency in the BogoMIPS field of /proc/cpuinfo, so libvirt > > > parsed that field and returned it through its API. > > > > > > However, not only many more boards don't report any value there, > > > but several - including ARMv8-based server hardware, and even the > > > more recent Raspberry Pi 3 - use this field as originally intended: > > > to report the BogoMIPS value instead of the CPU frequency. > > > > > > Since we have no way of detecting how the field is being used, > > > it's better to report no information at all rather than something > > > ludicrous like "your shiny 96-core aarch64 virtualization host's > > > CPUs are running at a whopping 100 MHz". > > > > Can we perhaps get useful freq data from sysfs instead ? I know my > > x86 machines report freq there, but I'm unsure if that reporting > > is x86-specific or not. > > The plan is to start using dmidecode(8) to retrieve the CPU > frequency, since AIUI it's already doing some work to locate the > information and process it and it would be quite pointless to > duplicate all that in libvirt. Plus we're already using the tool > for other stuff. > > I think that would only work on server-grade aarch64 hardware, > though, because most other ARM hardware will simply not expose > the information we need; even in that case, not reporting any > CPU frequency is better than reporting a completely bogus value. > > So basically reporting the actual CPU frequency when possible is > in my TODO list[1], but I believe there's value in merging this > series as-is since it already improves significantly on the > status quo. Sure, that's fine. I wasn't objecting to merging this series, just wondering where we might find the useful data in future. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
