Hi Catalin, On Monday 17 Feb 2025 at 14:57:53 (+0000), Catalin Marinas wrote: > On Mon, Feb 17, 2025 at 12:52:44PM +0100, Rafael J. Wysocki wrote: > > On Fri, Jan 31, 2025 at 5:25 PM Beata Michalska <beata.michalska@xxxxxxx> wrote: > > > > > > Currently the CPUFreq core exposes two sysfs attributes that can be used > > > to query current frequency of a given CPU(s): namely cpuinfo_cur_freq > > > and scaling_cur_freq. Both provide slightly different view on the > > > subject and they do come with their own drawbacks. > > > > > > cpuinfo_cur_freq provides higher precision though at a cost of being > > > rather expensive. Moreover, the information retrieved via this attribute > > > is somewhat short lived as frequency can change at any point of time > > > making it difficult to reason from. > > > > > > scaling_cur_freq, on the other hand, tends to be less accurate but then > > > the actual level of precision (and source of information) varies between > > > architectures making it a bit ambiguous. > > > > > > The new attribute, cpuinfo_avg_freq, is intended to provide more stable, > > > distinct interface, exposing an average frequency of a given CPU(s), as > > > reported by the hardware, over a time frame spanning no more than a few > > > milliseconds. As it requires appropriate hardware support, this > > > interface is optional. > > > > > > Note that under the hood, the new attribute relies on the information > > > provided by arch_freq_get_on_cpu, which, up to this point, has been > > > feeding data for scaling_cur_freq attribute, being the source of > > > ambiguity when it comes to interpretation. This has been amended by > > > restoring the intended behavior for scaling_cur_freq, with a new > > > dedicated config option to maintain status quo for those, who may need > > > it. > > > > In case anyone is waiting for my input here > > > > Acked-by: Rafael J. Wysocki <rafael@xxxxxxxxxx> > > > > for this and the previous patch and please feel free to route them > > both through ARM64. > > Thanks Rafael. I indeed plan to take them through the arm64 tree. Just a mention that this set depends on the patch that Beata linked at [6]. That patch applies cleanly on next-20250217 and it still builds/boots/works as expected. Thanks, Ionela. > > -- > Catalin
