On Mon, Mar 11, 2024 at 11:27:27AM -0700, Vanshidhar Konda wrote: > On Thu, Mar 07, 2024 at 11:17:26AM +0800, lihuisong (C) wrote: > > > > 在 2024/3/1 0:25, Vanshidhar Konda 写道: > > > AMU counters do not increment while a CPU is in idle. Saving the value > > > of the core and constant counters prior to invoking WFI allows FIE to > > > compute the frequency of a CPU that is idle. > > > > > > Signed-off-by: Vanshidhar Konda <vanshikonda@xxxxxxxxxxxxxxxxxxxxxx> > > > --- > > > arch/arm64/kernel/idle.c | 10 ++++++++++ > > > arch/arm64/kernel/topology.c | 14 ++++++++------ > > > 2 files changed, 18 insertions(+), 6 deletions(-) > > > > > > diff --git a/arch/arm64/kernel/idle.c b/arch/arm64/kernel/idle.c > > > index 05cfb347ec26..5ed2e57188a8 100644 > > > --- a/arch/arm64/kernel/idle.c > > > +++ b/arch/arm64/kernel/idle.c > > > @@ -26,6 +26,16 @@ void __cpuidle cpu_do_idle(void) > > > arm_cpuidle_save_irq_context(&context); > > > +#ifdef CONFIG_ARM64_AMU_EXTN > > > + /* Update the AMU counters before entering WFI. The cached AMU counter > > > + * value is used to determine CPU frequency while the CPU is idle > > > + * without needing to wake up the CPU. > > > + */ > > > + > > > + if (cpu_has_amu_feat(smp_processor_id())) > > > + update_freq_counters_refs(); > > > +#endif > > The below point I has mentioned in [1]. > > This is just for the WFI state. > > What about other deeper idle states, like retention and power down? > > The path to enter idle state is different for them. We should do this > > for all idle states. > > > > Yes. That makes sense. I'll account for them in the next version of the > patch. I'll work on the next version of the patch based on the updated > patch from @Beata. > This should now be covered by [1] --- [1]https://lore.kernel.org/all/20240312083431.3239989-4-beata.michalska@xxxxxxx/ --- BR Beata > Thanks, > Vanshi > > > > + > > > dsb(sy); > > > wfi(); > > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > > > index db8d14525cf4..8905eb0c681f 100644 > > > --- a/arch/arm64/kernel/topology.c > > > +++ b/arch/arm64/kernel/topology.c > > > @@ -240,13 +240,15 @@ unsigned int arch_freq_get_on_cpu(int cpu) > > > } while (read_seqcount_retry(&cpu_sample->seq, seq)); > > > /* > > > - * Bail on invalid count and when the last update was too long ago, > > > - * which covers idle and NOHZ full CPUs. > > > + * Bail on invalid count and when the last update was too long ago. > > > + * This covers idle, NOHZ full and isolated CPUs. > > > + * > > > + * Idle CPUs don't need to be measured because AMU counters stop > > > + * incrementing during WFI/WFE. > > > */ > > > - if (!delta_const_cnt || ((jiffies - last) > MAX_SAMPLE_AGE)) { > > > - if (!(housekeeping_cpu(cpu, HK_TYPE_TICK) && idle_cpu(cpu))) > > > - goto fallback; > > > - } > > > + if (!delta_const_cnt || > > > + ((jiffies - last) > MAX_SAMPLE_AGE && !idle_cpu(cpu))) > > > + goto fallback; > > > /* > > > * CPU frequency = reference perf (in Hz) * (/\ delivered) / (/\ reference) > > [1] https://lore.kernel.org/linux-arm-kernel/20231212072617.14756-1-lihuisong@xxxxxxxxxx/ > >
