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Message-ID: <20230328234149.GB8958@ranerica-svr.sc.intel.com>
Date: Tue, 28 Mar 2023 16:41:49 -0700
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Ricardo Neri <ricardo.neri@...el.com>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Ben Segall <bsegall@...gle.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Len Brown <len.brown@...el.com>, Mel Gorman <mgorman@...e.de>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Steven Rostedt <rostedt@...dmis.org>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Valentin Schneider <vschneid@...hat.com>,
Lukasz Luba <lukasz.luba@....com>,
Ionela Voinescu <ionela.voinescu@....com>, x86@...nel.org,
"Joel Fernandes (Google)" <joel@...lfernandes.org>,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
"Tim C . Chen" <tim.c.chen@...el.com>
Subject: Re: [PATCH v3 14/24] thermal: intel: hfi: Update the IPC class of
the current task
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@...ux.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@...gle.com>
> > Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
> > Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> > Cc: Ionela Voinescu <ionela.voinescu@....com>
> > Cc: Joel Fernandes (Google) <joel@...lfernandes.org>
> > Cc: Len Brown <len.brown@...el.com>
> > Cc: Lukasz Luba <lukasz.luba@....com>
> > Cc: Mel Gorman <mgorman@...e.de>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> > Cc: Steven Rostedt <rostedt@...dmis.org>
> > Cc: Tim C. Chen <tim.c.chen@...el.com>
> > Cc: Valentin Schneider <vschneid@...hat.com>
> > Cc: x86@...nel.org
> > Cc: linux-pm@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.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))
> > --
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