On Mon, Mar 01, 2021 at 12:21:17PM +0530, Viresh Kumar wrote: > This patch attempts to make it generic enough so other parts of the > kernel can also provide their own implementation of scale_freq_tick() > callback, which is called by the scheduler periodically to update the > per-cpu freq_scale variable. > > The implementations now need to provide 'struct scale_freq_data' for the > CPUs for which they have hardware counters available, and a callback > gets registered for each possible CPU in a per-cpu variable. > > The arch specific (or ARM AMU) counters are updated to adapt to this and > they take the highest priority if they are available, i.e. they will be > used instead of CPPC based counters for example. > > The special code to rebuild the sched domains, in case invariance status > change for the system, is moved out of arm64 specific code and is added > to arch_topology.c. > > Note that this also defines SCALE_FREQ_SOURCE_CPUFREQ but doesn't use it > and it is added to show that cpufreq is also acts as source of > information for FIE and will be used by default if no other counters are > supported for a platform. > > Reviewed-by: Ionela Voinescu <[email protected]> > Tested-by: Ionela Voinescu <[email protected]> > Signed-off-by: Viresh Kumar <[email protected]> > --- > arch/arm64/include/asm/topology.h | 10 +-- > arch/arm64/kernel/topology.c | 105 +++++++++++------------------- > drivers/base/arch_topology.c | 85 ++++++++++++++++++++++-- > include/linux/arch_topology.h | 14 +++- > 4 files changed, 134 insertions(+), 80 deletions(-)
For the arm64 bits: Acked-by: Will Deacon <[email protected]> However... > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index de8587cc119e..8f62dbf93f67 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -21,17 +21,94 @@ > #include <linux/sched.h> > #include <linux/smp.h> > > +static DEFINE_PER_CPU(struct scale_freq_data *, sft_data); > +static struct cpumask scale_freq_counters_mask; > +static bool scale_freq_invariant; > + > +static bool supports_scale_freq_counters(const struct cpumask *cpus) > +{ > + return cpumask_subset(cpus, &scale_freq_counters_mask); > +} > + > bool topology_scale_freq_invariant(void) > { > return cpufreq_supports_freq_invariance() || > - arch_freq_counters_available(cpu_online_mask); > + supports_scale_freq_counters(cpu_online_mask); > } > > -__weak bool arch_freq_counters_available(const struct cpumask *cpus) > +static void update_scale_freq_invariant(bool status) > { > - return false; > + if (scale_freq_invariant == status) > + return; > + > + /* > + * Task scheduler behavior depends on frequency invariance support, > + * either cpufreq or counter driven. If the support status changes as > + * a result of counter initialisation and use, retrigger the build of > + * scheduling domains to ensure the information is propagated properly. > + */ > + if (topology_scale_freq_invariant() == status) { > + scale_freq_invariant = status; > + rebuild_sched_domains_energy(); > + } > } > + > +void topology_set_scale_freq_source(struct scale_freq_data *data, > + const struct cpumask *cpus) > +{ > + struct scale_freq_data *sfd; > + int cpu; > + > + /* > + * Avoid calling rebuild_sched_domains() unnecessarily if FIE is > + * supported by cpufreq. > + */ > + if (cpumask_empty(&scale_freq_counters_mask)) > + scale_freq_invariant = topology_scale_freq_invariant(); > + > + for_each_cpu(cpu, cpus) { > + sfd = per_cpu(sft_data, cpu); > + > + /* Use ARCH provided counters whenever possible */ > + if (!sfd || sfd->source != SCALE_FREQ_SOURCE_ARCH) { > + per_cpu(sft_data, cpu) = data; > + cpumask_set_cpu(cpu, &scale_freq_counters_mask); > + } > + } > + > + update_scale_freq_invariant(true); > +} > +EXPORT_SYMBOL_GPL(topology_set_scale_freq_source); I don't get why you need to export this in this patch. The arm64 topology code is never built as a module. > + > +void topology_clear_scale_freq_source(enum scale_freq_source source, > + const struct cpumask *cpus) > +{ > + struct scale_freq_data *sfd; > + int cpu; > + > + for_each_cpu(cpu, cpus) { > + sfd = per_cpu(sft_data, cpu); > + > + if (sfd && sfd->source == source) { > + per_cpu(sft_data, cpu) = NULL; > + cpumask_clear_cpu(cpu, &scale_freq_counters_mask); > + } > + } > + > + update_scale_freq_invariant(false); > +} > +EXPORT_SYMBOL_GPL(topology_clear_scale_freq_source); Same here. > + > +void topology_scale_freq_tick(void) > +{ > + struct scale_freq_data *sfd = *this_cpu_ptr(&sft_data); > + > + if (sfd) > + sfd->set_freq_scale(); > +} > + > DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE; > +EXPORT_SYMBOL_GPL(freq_scale); And here. This one probably wants a less generic name as well if it's going to be exported. Will
