Messages in this thread | | | Date | Thu, 6 Oct 2022 11:14:55 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 15/23] thermal: intel: hfi: Report per-cpu class-specific performance scores |
| |
On Thu, Oct 06, 2022 at 10:52:16AM +0200, Peter Zijlstra wrote: > On Wed, Oct 05, 2022 at 04:59:59PM -0700, Ricardo Neri wrote: > > On Tue, Sep 27, 2022 at 01:59:15PM +0200, Peter Zijlstra wrote: > > > On Fri, Sep 09, 2022 at 04:11:57PM -0700, Ricardo Neri wrote: > > > > Support the arch_get_task_class_score() interface of the scheduler. Use the > > > > data that Intel Thread Director provides to inform the scheduler the > > > > performance of a class of tasks when placed on a given CPU. > > > > > > > > > > > +static void get_one_hfi_cap(struct hfi_instance *hfi_instance, s16 index, > > > > + struct hfi_cpu_data *hfi_caps, int class) > > > > +{ > > > > + struct hfi_cpu_data *caps; > > > > + > > > > + /* Find the capabilities of @cpu */ > > > > + caps = hfi_instance->data + index * hfi_features.cpu_stride + > > > > + class * hfi_features.class_stride; > > > > + memcpy(hfi_caps, caps, sizeof(*hfi_caps)); > > > > +} > > > > + > > > > +int intel_hfi_get_task_class_score(int class, int cpu) > > > > +{ > > > > + struct hfi_cpu_info *info = &per_cpu(hfi_cpu_info, cpu); > > > > + struct hfi_instance *instance; > > > > + struct hfi_cpu_data caps; > > > > + unsigned long flags; > > > > + int cap; > > > > + > > > > + if (cpu < 0 || cpu >= nr_cpu_ids) > > > > + return -EINVAL; > > > > + > > > > + if (class == TASK_CLASS_UNCLASSIFIED) > > > > + return -EINVAL; > > > > + > > > > + if (class >= (int)hfi_features.nr_classes) > > > > + return -EINVAL; > > > > + > > > > + instance = info->hfi_instance; > > > > + if (!instance) > > > > + return -ENOENT; > > > > + > > > > + raw_spin_lock_irqsave(&instance->table_lock, flags); > > > > + get_one_hfi_cap(instance, info->index, &caps, class); > > > > + cap = caps.perf_cap; > > > > + raw_spin_unlock_irqrestore(&instance->table_lock, flags); > > > > + > > > > + return cap; > > > > +} > > > > > > Does any of that data actually ever change? Isn't the class score fixed > > > per CPU type? > > > > Yes, data can change. The Intel SDM Vol 3 Section 14.6.7 states that the > > table can be updated during runtime. > > I find the SDM is often unreadable gibberish, this part doesn't dissapoint. > > There's a ton of might and maybe there; what does it actually do and how > often does it do it? Given the thermal interrupt is such a shitshow, we > really, as in *REALLY* don't want this to happen at any frequency at > all. > > And if it barely happens, why do we care if it happens at all?
I enabled this HFI crud on my ADL (INTEL_HFI_THERMAL -- because apparently Debian doesn't default enable this) and now I get all of _1_ interrupt during boot.
Building a kernel on that machine doesn't manage to trip another one.
TRM: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Thermal event interrupts
So yeah.. *can* change, but doesn't.
| |