Mailing List Archive

[PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of the current task
Use Intel Thread Director classification to update the IPC class of a
task. Implement the arch_update_ipcc() interface of the scheduler.

Cc: Ben Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim C. Chen <tim.c.chen@intel.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: x86@kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
---
Changes since v2:
* Removed the implementation of arch_has_ipc_classes().

Changes since v1:
* Adjusted the result the classification of Intel Thread Director to start
at class 1. Class 0 for the scheduler means that the task is
unclassified.
* Redefined union hfi_thread_feedback_char_msr to ensure all
bit-fields are packed. (PeterZ)
* Removed CONFIG_INTEL_THREAD_DIRECTOR. (PeterZ)
* Shortened the names of the functions that implement IPC classes.
* Removed argument smt_siblings_idle from intel_hfi_update_ipcc().
(PeterZ)
---
arch/x86/include/asm/topology.h | 6 ++++++
drivers/thermal/intel/intel_hfi.c | 32 +++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 458c891a8273..ffcdac3f398f 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -227,4 +227,10 @@ void init_freq_invariance_cppc(void);
#define arch_init_invariance_cppc init_freq_invariance_cppc
#endif

+#if defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL)
+void intel_hfi_update_ipcc(struct task_struct *curr);
+
+#define arch_update_ipcc intel_hfi_update_ipcc
+#endif /* defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL) */
+
#endif /* _ASM_X86_TOPOLOGY_H */
diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
index b06021828892..530dcf57e06e 100644
--- a/drivers/thermal/intel/intel_hfi.c
+++ b/drivers/thermal/intel/intel_hfi.c
@@ -72,6 +72,17 @@ union cpuid6_edx {
u32 full;
};

+#ifdef CONFIG_IPC_CLASSES
+union hfi_thread_feedback_char_msr {
+ struct {
+ u64 classid : 8;
+ u64 __reserved : 55;
+ u64 valid : 1;
+ } split;
+ u64 full;
+};
+#endif
+
/**
* struct hfi_cpu_data - HFI capabilities per CPU
* @perf_cap: Performance capability
@@ -174,6 +185,27 @@ static struct workqueue_struct *hfi_updates_wq;
#ifdef CONFIG_IPC_CLASSES
static int __percpu *hfi_ipcc_scores;

+void intel_hfi_update_ipcc(struct task_struct *curr)
+{
+ union hfi_thread_feedback_char_msr msr;
+
+ /* We should not be here if ITD is not supported. */
+ if (!cpu_feature_enabled(X86_FEATURE_ITD)) {
+ pr_warn_once("task classification requested but not supported!");
+ return;
+ }
+
+ rdmsrl(MSR_IA32_HW_FEEDBACK_CHAR, msr.full);
+ if (!msr.split.valid)
+ return;
+
+ /*
+ * 0 is a valid classification for Intel Thread Director. A scheduler
+ * IPCC class of 0 means that the task is unclassified. Adjust.
+ */
+ curr->ipcc = msr.split.classid + 1;
+}
+
static int alloc_hfi_ipcc_scores(void)
{
if (!cpu_feature_enabled(X86_FEATURE_ITD))
--
2.25.1
Re: [PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of the current task [ In reply to ]
On Tue, Feb 7, 2023 at 6:02?AM Ricardo Neri
<ricardo.neri-calderon@linux.intel.com> wrote:
>
> Use Intel Thread Director classification to update the IPC class of a
> task. Implement the arch_update_ipcc() interface of the scheduler.
>
> Cc: Ben Segall <bsegall@google.com>
> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Ionela Voinescu <ionela.voinescu@arm.com>
> Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Lukasz Luba <lukasz.luba@arm.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Tim C. Chen <tim.c.chen@intel.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: x86@kernel.org
> Cc: linux-pm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> ---
> Changes since v2:
> * Removed the implementation of arch_has_ipc_classes().
>
> Changes since v1:
> * Adjusted the result the classification of Intel Thread Director to start
> at class 1. Class 0 for the scheduler means that the task is
> unclassified.
> * Redefined union hfi_thread_feedback_char_msr to ensure all
> bit-fields are packed. (PeterZ)
> * Removed CONFIG_INTEL_THREAD_DIRECTOR. (PeterZ)
> * Shortened the names of the functions that implement IPC classes.
> * Removed argument smt_siblings_idle from intel_hfi_update_ipcc().
> (PeterZ)
> ---
> arch/x86/include/asm/topology.h | 6 ++++++
> drivers/thermal/intel/intel_hfi.c | 32 +++++++++++++++++++++++++++++++
> 2 files changed, 38 insertions(+)
>
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index 458c891a8273..ffcdac3f398f 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -227,4 +227,10 @@ void init_freq_invariance_cppc(void);
> #define arch_init_invariance_cppc init_freq_invariance_cppc
> #endif
>
> +#if defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL)
> +void intel_hfi_update_ipcc(struct task_struct *curr);
> +
> +#define arch_update_ipcc intel_hfi_update_ipcc
> +#endif /* defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL) */
> +
> #endif /* _ASM_X86_TOPOLOGY_H */
> diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
> index b06021828892..530dcf57e06e 100644
> --- a/drivers/thermal/intel/intel_hfi.c
> +++ b/drivers/thermal/intel/intel_hfi.c
> @@ -72,6 +72,17 @@ union cpuid6_edx {
> u32 full;
> };
>
> +#ifdef CONFIG_IPC_CLASSES
> +union hfi_thread_feedback_char_msr {
> + struct {
> + u64 classid : 8;
> + u64 __reserved : 55;
> + u64 valid : 1;
> + } split;
> + u64 full;
> +};
> +#endif
> +
> /**
> * struct hfi_cpu_data - HFI capabilities per CPU
> * @perf_cap: Performance capability
> @@ -174,6 +185,27 @@ static struct workqueue_struct *hfi_updates_wq;
> #ifdef CONFIG_IPC_CLASSES
> static int __percpu *hfi_ipcc_scores;
>
> +void intel_hfi_update_ipcc(struct task_struct *curr)
> +{
> + union hfi_thread_feedback_char_msr msr;
> +
> + /* We should not be here if ITD is not supported. */
> + if (!cpu_feature_enabled(X86_FEATURE_ITD)) {
> + pr_warn_once("task classification requested but not supported!");
> + return;
> + }
> +
> + rdmsrl(MSR_IA32_HW_FEEDBACK_CHAR, msr.full);
> + if (!msr.split.valid)
> + return;
> +
> + /*
> + * 0 is a valid classification for Intel Thread Director. A scheduler
> + * IPCC class of 0 means that the task is unclassified. Adjust.
> + */
> + curr->ipcc = msr.split.classid + 1;
> +}

Wouldn't it be better to return the adjusted value from this function
and let the caller store it where appropriate?

It doesn't look like it is necessary to pass the task_struct pointer to it.

> +
> static int alloc_hfi_ipcc_scores(void)
> {
> if (!cpu_feature_enabled(X86_FEATURE_ITD))
> --
Re: [PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of the current task [ In reply to ]
On Mon, Mar 27, 2023 at 06:42:28PM +0200, Rafael J. Wysocki wrote:
> On Tue, Feb 7, 2023 at 6:02?AM Ricardo Neri
> <ricardo.neri-calderon@linux.intel.com> wrote:
> >
> > Use Intel Thread Director classification to update the IPC class of a
> > task. Implement the arch_update_ipcc() interface of the scheduler.
> >
> > Cc: Ben Segall <bsegall@google.com>
> > Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> > Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> > Cc: Ionela Voinescu <ionela.voinescu@arm.com>
> > Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: Lukasz Luba <lukasz.luba@arm.com>
> > Cc: Mel Gorman <mgorman@suse.de>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Tim C. Chen <tim.c.chen@intel.com>
> > Cc: Valentin Schneider <vschneid@redhat.com>
> > Cc: x86@kernel.org
> > Cc: linux-pm@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > ---
> > Changes since v2:
> > * Removed the implementation of arch_has_ipc_classes().
> >
> > Changes since v1:
> > * Adjusted the result the classification of Intel Thread Director to start
> > at class 1. Class 0 for the scheduler means that the task is
> > unclassified.
> > * Redefined union hfi_thread_feedback_char_msr to ensure all
> > bit-fields are packed. (PeterZ)
> > * Removed CONFIG_INTEL_THREAD_DIRECTOR. (PeterZ)
> > * Shortened the names of the functions that implement IPC classes.
> > * Removed argument smt_siblings_idle from intel_hfi_update_ipcc().
> > (PeterZ)
> > ---
> > arch/x86/include/asm/topology.h | 6 ++++++
> > drivers/thermal/intel/intel_hfi.c | 32 +++++++++++++++++++++++++++++++
> > 2 files changed, 38 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> > index 458c891a8273..ffcdac3f398f 100644
> > --- a/arch/x86/include/asm/topology.h
> > +++ b/arch/x86/include/asm/topology.h
> > @@ -227,4 +227,10 @@ void init_freq_invariance_cppc(void);
> > #define arch_init_invariance_cppc init_freq_invariance_cppc
> > #endif
> >
> > +#if defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL)
> > +void intel_hfi_update_ipcc(struct task_struct *curr);
> > +
> > +#define arch_update_ipcc intel_hfi_update_ipcc
> > +#endif /* defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL) */
> > +
> > #endif /* _ASM_X86_TOPOLOGY_H */
> > diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
> > index b06021828892..530dcf57e06e 100644
> > --- a/drivers/thermal/intel/intel_hfi.c
> > +++ b/drivers/thermal/intel/intel_hfi.c
> > @@ -72,6 +72,17 @@ union cpuid6_edx {
> > u32 full;
> > };
> >
> > +#ifdef CONFIG_IPC_CLASSES
> > +union hfi_thread_feedback_char_msr {
> > + struct {
> > + u64 classid : 8;
> > + u64 __reserved : 55;
> > + u64 valid : 1;
> > + } split;
> > + u64 full;
> > +};
> > +#endif
> > +
> > /**
> > * struct hfi_cpu_data - HFI capabilities per CPU
> > * @perf_cap: Performance capability
> > @@ -174,6 +185,27 @@ static struct workqueue_struct *hfi_updates_wq;
> > #ifdef CONFIG_IPC_CLASSES
> > static int __percpu *hfi_ipcc_scores;
> >
> > +void intel_hfi_update_ipcc(struct task_struct *curr)
> > +{
> > + union hfi_thread_feedback_char_msr msr;
> > +
> > + /* We should not be here if ITD is not supported. */
> > + if (!cpu_feature_enabled(X86_FEATURE_ITD)) {
> > + pr_warn_once("task classification requested but not supported!");
> > + return;
> > + }
> > +
> > + rdmsrl(MSR_IA32_HW_FEEDBACK_CHAR, msr.full);
> > + if (!msr.split.valid)
> > + return;
> > +
> > + /*
> > + * 0 is a valid classification for Intel Thread Director. A scheduler
> > + * IPCC class of 0 means that the task is unclassified. Adjust.
> > + */
> > + curr->ipcc = msr.split.classid + 1;
> > +}
>
> Wouldn't it be better to return the adjusted value from this function
> and let the caller store it where appropriate?
>
> It doesn't look like it is necessary to pass the task_struct pointer to it.

Judging from this patch alone, yes, it does not make much sense to pass a
task_struct as argument. In patch 21, however, this function uses various
members of task_struct and makes it more convenient to have it as argument,
no?

>
> > +
> > static int alloc_hfi_ipcc_scores(void)
> > {
> > if (!cpu_feature_enabled(X86_FEATURE_ITD))
> > --
Re: [PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of the current task [ In reply to ]
On Wed, Mar 29, 2023 at 1:31?AM Ricardo Neri
<ricardo.neri-calderon@linux.intel.com> wrote:
>
> On Mon, Mar 27, 2023 at 06:42:28PM +0200, Rafael J. Wysocki wrote:
> > On Tue, Feb 7, 2023 at 6:02?AM Ricardo Neri
> > <ricardo.neri-calderon@linux.intel.com> wrote:
> > >
> > > Use Intel Thread Director classification to update the IPC class of a
> > > task. Implement the arch_update_ipcc() interface of the scheduler.
> > >
> > > Cc: Ben Segall <bsegall@google.com>
> > > Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> > > Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> > > Cc: Ionela Voinescu <ionela.voinescu@arm.com>
> > > Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
> > > Cc: Len Brown <len.brown@intel.com>
> > > Cc: Lukasz Luba <lukasz.luba@arm.com>
> > > Cc: Mel Gorman <mgorman@suse.de>
> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> > > Cc: Steven Rostedt <rostedt@goodmis.org>
> > > Cc: Tim C. Chen <tim.c.chen@intel.com>
> > > Cc: Valentin Schneider <vschneid@redhat.com>
> > > Cc: x86@kernel.org
> > > Cc: linux-pm@vger.kernel.org
> > > Cc: linux-kernel@vger.kernel.org
> > > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > > ---
> > > Changes since v2:
> > > * Removed the implementation of arch_has_ipc_classes().
> > >
> > > Changes since v1:
> > > * Adjusted the result the classification of Intel Thread Director to start
> > > at class 1. Class 0 for the scheduler means that the task is
> > > unclassified.
> > > * Redefined union hfi_thread_feedback_char_msr to ensure all
> > > bit-fields are packed. (PeterZ)
> > > * Removed CONFIG_INTEL_THREAD_DIRECTOR. (PeterZ)
> > > * Shortened the names of the functions that implement IPC classes.
> > > * Removed argument smt_siblings_idle from intel_hfi_update_ipcc().
> > > (PeterZ)
> > > ---
> > > arch/x86/include/asm/topology.h | 6 ++++++
> > > drivers/thermal/intel/intel_hfi.c | 32 +++++++++++++++++++++++++++++++
> > > 2 files changed, 38 insertions(+)
> > >
> > > diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> > > index 458c891a8273..ffcdac3f398f 100644
> > > --- a/arch/x86/include/asm/topology.h
> > > +++ b/arch/x86/include/asm/topology.h
> > > @@ -227,4 +227,10 @@ void init_freq_invariance_cppc(void);
> > > #define arch_init_invariance_cppc init_freq_invariance_cppc
> > > #endif
> > >
> > > +#if defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL)
> > > +void intel_hfi_update_ipcc(struct task_struct *curr);
> > > +
> > > +#define arch_update_ipcc intel_hfi_update_ipcc
> > > +#endif /* defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL) */
> > > +
> > > #endif /* _ASM_X86_TOPOLOGY_H */
> > > diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
> > > index b06021828892..530dcf57e06e 100644
> > > --- a/drivers/thermal/intel/intel_hfi.c
> > > +++ b/drivers/thermal/intel/intel_hfi.c
> > > @@ -72,6 +72,17 @@ union cpuid6_edx {
> > > u32 full;
> > > };
> > >
> > > +#ifdef CONFIG_IPC_CLASSES
> > > +union hfi_thread_feedback_char_msr {
> > > + struct {
> > > + u64 classid : 8;
> > > + u64 __reserved : 55;
> > > + u64 valid : 1;
> > > + } split;
> > > + u64 full;
> > > +};
> > > +#endif
> > > +
> > > /**
> > > * struct hfi_cpu_data - HFI capabilities per CPU
> > > * @perf_cap: Performance capability
> > > @@ -174,6 +185,27 @@ static struct workqueue_struct *hfi_updates_wq;
> > > #ifdef CONFIG_IPC_CLASSES
> > > static int __percpu *hfi_ipcc_scores;
> > >
> > > +void intel_hfi_update_ipcc(struct task_struct *curr)
> > > +{
> > > + union hfi_thread_feedback_char_msr msr;
> > > +
> > > + /* We should not be here if ITD is not supported. */
> > > + if (!cpu_feature_enabled(X86_FEATURE_ITD)) {
> > > + pr_warn_once("task classification requested but not supported!");
> > > + return;
> > > + }
> > > +
> > > + rdmsrl(MSR_IA32_HW_FEEDBACK_CHAR, msr.full);
> > > + if (!msr.split.valid)
> > > + return;
> > > +
> > > + /*
> > > + * 0 is a valid classification for Intel Thread Director. A scheduler
> > > + * IPCC class of 0 means that the task is unclassified. Adjust.
> > > + */
> > > + curr->ipcc = msr.split.classid + 1;
> > > +}
> >
> > Wouldn't it be better to return the adjusted value from this function
> > and let the caller store it where appropriate?
> >
> > It doesn't look like it is necessary to pass the task_struct pointer to it.
>
> Judging from this patch alone, yes, it does not make much sense to pass a
> task_struct as argument. In patch 21, however, this function uses various
> members of task_struct and makes it more convenient to have it as argument,
> no?

I'm not convinced about this, but anyway it is better to combine the
two patches in such cases IMO.

The way it is done now confuses things from my perspective.

> >
> > > +
> > > static int alloc_hfi_ipcc_scores(void)
> > > {
> > > if (!cpu_feature_enabled(X86_FEATURE_ITD))
> > > --
Re: [PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of the current task [ In reply to ]
On Wed, Mar 29, 2023 at 02:13:29PM +0200, Rafael J. Wysocki wrote:
> On Wed, Mar 29, 2023 at 1:31?AM Ricardo Neri
> <ricardo.neri-calderon@linux.intel.com> wrote:
> >
> > On Mon, Mar 27, 2023 at 06:42:28PM +0200, Rafael J. Wysocki wrote:
> > > On Tue, Feb 7, 2023 at 6:02?AM Ricardo Neri
> > > <ricardo.neri-calderon@linux.intel.com> wrote:
> > > >
> > > > Use Intel Thread Director classification to update the IPC class of a
> > > > task. Implement the arch_update_ipcc() interface of the scheduler.
> > > >
> > > > Cc: Ben Segall <bsegall@google.com>
> > > > Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> > > > Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> > > > Cc: Ionela Voinescu <ionela.voinescu@arm.com>
> > > > Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
> > > > Cc: Len Brown <len.brown@intel.com>
> > > > Cc: Lukasz Luba <lukasz.luba@arm.com>
> > > > Cc: Mel Gorman <mgorman@suse.de>
> > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> > > > Cc: Steven Rostedt <rostedt@goodmis.org>
> > > > Cc: Tim C. Chen <tim.c.chen@intel.com>
> > > > Cc: Valentin Schneider <vschneid@redhat.com>
> > > > Cc: x86@kernel.org
> > > > Cc: linux-pm@vger.kernel.org
> > > > Cc: linux-kernel@vger.kernel.org
> > > > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > > > ---
> > > > Changes since v2:
> > > > * Removed the implementation of arch_has_ipc_classes().
> > > >
> > > > Changes since v1:
> > > > * Adjusted the result the classification of Intel Thread Director to start
> > > > at class 1. Class 0 for the scheduler means that the task is
> > > > unclassified.
> > > > * Redefined union hfi_thread_feedback_char_msr to ensure all
> > > > bit-fields are packed. (PeterZ)
> > > > * Removed CONFIG_INTEL_THREAD_DIRECTOR. (PeterZ)
> > > > * Shortened the names of the functions that implement IPC classes.
> > > > * Removed argument smt_siblings_idle from intel_hfi_update_ipcc().
> > > > (PeterZ)
> > > > ---
> > > > arch/x86/include/asm/topology.h | 6 ++++++
> > > > drivers/thermal/intel/intel_hfi.c | 32 +++++++++++++++++++++++++++++++
> > > > 2 files changed, 38 insertions(+)
> > > >
> > > > diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> > > > index 458c891a8273..ffcdac3f398f 100644
> > > > --- a/arch/x86/include/asm/topology.h
> > > > +++ b/arch/x86/include/asm/topology.h
> > > > @@ -227,4 +227,10 @@ void init_freq_invariance_cppc(void);
> > > > #define arch_init_invariance_cppc init_freq_invariance_cppc
> > > > #endif
> > > >
> > > > +#if defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL)
> > > > +void intel_hfi_update_ipcc(struct task_struct *curr);
> > > > +
> > > > +#define arch_update_ipcc intel_hfi_update_ipcc
> > > > +#endif /* defined(CONFIG_IPC_CLASSES) && defined(CONFIG_INTEL_HFI_THERMAL) */
> > > > +
> > > > #endif /* _ASM_X86_TOPOLOGY_H */
> > > > diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
> > > > index b06021828892..530dcf57e06e 100644
> > > > --- a/drivers/thermal/intel/intel_hfi.c
> > > > +++ b/drivers/thermal/intel/intel_hfi.c
> > > > @@ -72,6 +72,17 @@ union cpuid6_edx {
> > > > u32 full;
> > > > };
> > > >
> > > > +#ifdef CONFIG_IPC_CLASSES
> > > > +union hfi_thread_feedback_char_msr {
> > > > + struct {
> > > > + u64 classid : 8;
> > > > + u64 __reserved : 55;
> > > > + u64 valid : 1;
> > > > + } split;
> > > > + u64 full;
> > > > +};
> > > > +#endif
> > > > +
> > > > /**
> > > > * struct hfi_cpu_data - HFI capabilities per CPU
> > > > * @perf_cap: Performance capability
> > > > @@ -174,6 +185,27 @@ static struct workqueue_struct *hfi_updates_wq;
> > > > #ifdef CONFIG_IPC_CLASSES
> > > > static int __percpu *hfi_ipcc_scores;
> > > >
> > > > +void intel_hfi_update_ipcc(struct task_struct *curr)
> > > > +{
> > > > + union hfi_thread_feedback_char_msr msr;
> > > > +
> > > > + /* We should not be here if ITD is not supported. */
> > > > + if (!cpu_feature_enabled(X86_FEATURE_ITD)) {
> > > > + pr_warn_once("task classification requested but not supported!");
> > > > + return;
> > > > + }
> > > > +
> > > > + rdmsrl(MSR_IA32_HW_FEEDBACK_CHAR, msr.full);
> > > > + if (!msr.split.valid)
> > > > + return;
> > > > +
> > > > + /*
> > > > + * 0 is a valid classification for Intel Thread Director. A scheduler
> > > > + * IPCC class of 0 means that the task is unclassified. Adjust.
> > > > + */
> > > > + curr->ipcc = msr.split.classid + 1;
> > > > +}
> > >
> > > Wouldn't it be better to return the adjusted value from this function
> > > and let the caller store it where appropriate?
> > >
> > > It doesn't look like it is necessary to pass the task_struct pointer to it.
> >
> > Judging from this patch alone, yes, it does not make much sense to pass a
> > task_struct as argument. In patch 21, however, this function uses various
> > members of task_struct and makes it more convenient to have it as argument,
> > no?
>
> I'm not convinced about this, but anyway it is better to combine the
> two patches in such cases IMO.
>
> The way it is done now confuses things from my perspective.

Right, I structured the patchset to have the additions to task_struct in
separate patches. This made it less clear for intel_hfi.c

Would it be acceptable if I kept void intel_hfi_update_ipcc(struct
task_struct *curr) and added a static function u32 intel_hfi_get_ipcc(void)
to return the hardware classification?

Otherwise, I would need to add three different accessors for task_struct
so that the HFI driver can retrieve the auxiliary members from patch 21.

Thanks and BR,
Ricardo