[04/11] sched,x86: Enable Turbo Boost Max Technology

Message ID	1471559812-19967-5-git-send-email-srinivas.pandruvada@linux.intel.com (mailing list archive)
State	Not Applicable, archived
Headers	show Return-Path: <linux-pm-owner@kernel.org> From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> To: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, rjw@rjwysocki.net, peterz@infradead.org Cc: x86@kernel.org, bp@suse.de, sudeep.holla@arm.com, ak@linux.intel.com, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, alexey.klimov@arm.com, viresh.kumar@linaro.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, lenb@kernel.org, tim.c.chen@linux.intel.com, srinivas.pandruvada@linux.intel.com, paul.gortmaker@windriver.com, jpoimboe@redhat.com, mcgrof@kernel.org, jgross@suse.com, robert.moore@intel.com, dvyukov@google.com, jeyu@redhat.com Subject: [PATCH 04/11] sched,x86: Enable Turbo Boost Max Technology Date: Thu, 18 Aug 2016 15:36:45 -0700 Message-Id: <1471559812-19967-5-git-send-email-srinivas.pandruvada@linux.intel.com> In-Reply-To: <1471559812-19967-1-git-send-email-srinivas.pandruvada@linux.intel.com> References: <1471559812-19967-1-git-send-email-srinivas.pandruvada@linux.intel.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c580d8c..c1d36db 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -928,6 +928,15 @@ config SCHED_MC making when dealing with multi-core CPU chips at a cost of slightly increased overhead in some places. If unsure say N here. +config SCHED_ITMT + bool "Intel Turbo Boost Max Technology (ITMT) scheduler support" + depends on SCHED_MC && CPU_SUP_INTEL && X86_INTEL_PSTATE + ---help--- + ITMT enabled scheduler support improves the CPU scheduler's decision + to move tasks to cpu core that can be boosted to a higher frequency + than others. It will have better performance at a cost of slightly + increased overhead in task migrations. If unsure say N here. + source "kernel/Kconfig.preempt" config UP_LATE_INIT diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index cf75871..f148843 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -146,4 +146,30 @@ struct pci_bus; int x86_pci_root_bus_node(int bus); void x86_pci_root_bus_resources(int bus, struct list_head *resources); +#ifdef CONFIG_SCHED_ITMT +DECLARE_PER_CPU_READ_MOSTLY(int, sched_core_priority); + +static inline bool sched_asym_prefer(int a, int b) +{ + return per_cpu(sched_core_priority, a) > per_cpu(sched_core_priority, b); +} + +#define sched_asym_prefer sched_asym_prefer + +/* Interface to set priority of a cpu */ +void sched_set_itmt_core_prio(int prio, int core_cpu); + +/* Interface to notify scheduler that system supports ITMT */ +void set_sched_itmt(bool support_itmt); + +#else /* CONFIG_SCHED_ITMT */ + +static inline void set_sched_itmt(bool support_itmt) +{ +} +static inline void sched_set_itmt_core_prio(int prio, int core_cpu) +{ +} +#endif /* CONFIG_SCHED_ITMT */ + #endif /* _ASM_X86_TOPOLOGY_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 0503f5b..2008335 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -124,6 +124,7 @@ obj-$(CONFIG_EFI) += sysfb_efi.o obj-$(CONFIG_PERF_EVENTS) += perf_regs.o obj-$(CONFIG_TRACING) += tracepoint.o +obj-$(CONFIG_SCHED_ITMT) += itmt.o ### # 64 bit specific files diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c new file mode 100644 index 0000000..a9470f5 --- /dev/null +++ b/arch/x86/kernel/itmt.c @@ -0,0 +1,147 @@ +/* + * itmt.c: Functions and data structures for enabling + * scheduler to favor scheduling on cores that + * can be boosted to a higher frequency using + * Intel Turbo Boost Max Technology 3.0 + * + * (C) Copyright 2016 Intel Corporation + * Author: Tim Chen <tim.c.chen@linux.intel.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ + +#include <linux/sched.h> +#include <linux/cpumask.h> +#include <linux/cpuset.h> +#include <asm/mutex.h> +#include <linux/sched.h> +#include <linux/sysctl.h> + +DEFINE_PER_CPU_READ_MOSTLY(int, sched_core_priority); +static DEFINE_MUTEX(itmt_update_mutex); + +static unsigned int zero = 0; +static unsigned int one = 1; + +/* + * Boolean to control whether we want to move processes to cpu capable + * of higher turbo frequency for cpus supporting Intel Turbo Boost Max + * Technology 3.0. + * + * It can be set via /proc/sys/kernel/sched_itmt_enabled + */ +unsigned int __read_mostly sysctl_sched_itmt_enabled = 0; + +/* + * The pstate_driver calls set_sched_itmt to indicate if the system + * is ITMT capable. + */ +static bool __read_mostly sched_itmt_capable; + +static void enable_sched_itmt(bool enable_itmt) +{ + mutex_lock(&itmt_update_mutex); + + sysctl_sched_itmt_enabled = enable_itmt; + regenerate_sched_domains(); + + mutex_unlock(&itmt_update_mutex); +} + +static int sched_itmt_update_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + int ret; + + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + if (ret || !write) + return ret; + + enable_sched_itmt(sysctl_sched_itmt_enabled); + + return ret; +} + +static struct ctl_table itmt_kern_table[] = { + { + .procname = "sched_itmt_enabled", + .data = &sysctl_sched_itmt_enabled, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sched_itmt_update_handler, + .extra1 = &zero, + .extra2 = &one, + }, + {} +}; + +static struct ctl_table itmt_root_table[] = { + { + .procname = "kernel", + .mode = 0555, + .child = itmt_kern_table, + }, + {} +}; + +static struct ctl_table_header *itmt_sysctl_header; + +/* + * The boot code will find out the max boost frequency + * and call this function to set a priority proportional + * to the max boost frequency. CPU with higher boost + * frequency will receive higher priority. + */ +void sched_set_itmt_core_prio(int prio, int core_cpu) +{ + int cpu, i = 1; + + for_each_cpu(cpu, topology_sibling_cpumask(core_cpu)) { + int smt_prio; + + /* + * Discount the priority of sibling so that we don't + * pack all loads to the same core before using other cores. + */ + smt_prio = prio * smp_num_siblings / i; + i++; + per_cpu(sched_core_priority, cpu) = smt_prio; + } +} + +/* + * During boot up, boot code will detect if the system + * is ITMT capable and call set_sched_itmt. + * + * This should be call after sched_set_itmt_core_prio + * has been called to set the cpus' priorities. + * + * This function should be called without cpu hot plug lock + * as we need to acquire the lock to rebuild sched domains + * later. + */ +void set_sched_itmt(bool itmt_capable) +{ + mutex_lock(&itmt_update_mutex); + + if (itmt_capable != sched_itmt_capable) { + + if (itmt_capable) { + itmt_sysctl_header = + register_sysctl_table(itmt_root_table); + } else { + if (itmt_sysctl_header) + unregister_sysctl_table(itmt_sysctl_header); + sysctl_sched_itmt_enabled = false; + } + + sched_itmt_capable = itmt_capable; + regenerate_sched_domains(); + } + + mutex_unlock(&itmt_update_mutex); +}

[04/11] sched,x86: Enable Turbo Boost Max Technology

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