Messages in this thread Patch in this message | | | From | Ricardo Neri <> | Subject | [PATCH v3 21/24] thermal: intel: hfi: Implement model-specific checks for task classification | Date | Mon, 6 Feb 2023 21:11:02 -0800 |
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In Alder Lake and Raptor Lake, the result of thread classification is more accurate when only one SMT sibling is busy. Classification results for class 2 and 3 are always reliable.
To avoid unnecessary migrations, only update the class of a task if it has been the same during 4 consecutive user ticks.
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: * None
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. * Used the new names of the IPC classes members in task_struct. * Reworked helper functions to use sched_smt_siblings_idle() to query the idle state of the SMT siblings of a CPU. --- drivers/thermal/intel/intel_hfi.c | 60 ++++++++++++++++++++++++++++++- 1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c index 35d947f47550..fdb53e4cabc1 100644 --- a/drivers/thermal/intel/intel_hfi.c +++ b/drivers/thermal/intel/intel_hfi.c @@ -40,6 +40,7 @@ #include <linux/workqueue.h> #include <asm/msr.h> +#include <asm/intel-family.h> #include "../thermal_core.h" #include "intel_hfi.h" @@ -209,9 +210,64 @@ static int __percpu *hfi_ipcc_scores; */ #define HFI_UNCLASSIFIED_DEFAULT 1 +#define CLASS_DEBOUNCER_SKIPS 4 + +/** + * debounce_and_update_class() - Process and update a task's classification + * + * @p: The task of which the classification will be updated + * @new_ipcc: The new IPC classification + * + * Update the classification of @p with the new value that hardware provides. + * Only update the classification of @p if it has been the same during + * CLASS_DEBOUNCER_SKIPS consecutive ticks. + */ +static void debounce_and_update_class(struct task_struct *p, u8 new_ipcc) +{ + u16 debounce_skip; + + /* The class of @p changed. Only restart the debounce counter. */ + if (p->ipcc_tmp != new_ipcc) { + p->ipcc_cntr = 1; + goto out; + } + + /* + * The class of @p did not change. Update it if it has been the same + * for CLASS_DEBOUNCER_SKIPS user ticks. + */ + debounce_skip = p->ipcc_cntr + 1; + if (debounce_skip < CLASS_DEBOUNCER_SKIPS) + p->ipcc_cntr++; + else + p->ipcc = new_ipcc; + +out: + p->ipcc_tmp = new_ipcc; +} + +static bool classification_is_accurate(u8 hfi_class, bool smt_siblings_idle) +{ + switch (boot_cpu_data.x86_model) { + case INTEL_FAM6_ALDERLAKE: + case INTEL_FAM6_ALDERLAKE_L: + case INTEL_FAM6_RAPTORLAKE: + case INTEL_FAM6_RAPTORLAKE_P: + case INTEL_FAM6_RAPTORLAKE_S: + if (hfi_class == 3 || hfi_class == 2 || smt_siblings_idle) + return true; + + return false; + + default: + return true; + } +} + void intel_hfi_update_ipcc(struct task_struct *curr) { union hfi_thread_feedback_char_msr msr; + bool idle; /* We should not be here if ITD is not supported. */ if (!cpu_feature_enabled(X86_FEATURE_ITD)) { @@ -227,7 +283,9 @@ void intel_hfi_update_ipcc(struct task_struct *curr) * 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; + idle = sched_smt_siblings_idle(task_cpu(curr)); + if (classification_is_accurate(msr.split.classid, idle)) + debounce_and_update_class(curr, msr.split.classid + 1); } unsigned long intel_hfi_get_ipcc_score(unsigned short ipcc, int cpu) -- 2.25.1
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