Re: [PATCH V5 1/2] topology: Allow multiple entities to provide sched_freq_tick() callback
From: Will Deacon <will@kernel.org>
Date: 2021-03-08 14:52:54
Also in:
linux-pm, lkml
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 <redacted> Tested-by: Ionela Voinescu <redacted> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- 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 <will@kernel.org> However...
quoted hunk ↗ jump to hunk
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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel