^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * sched_clock() for unstable CPU clocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) * Updates and enhancements:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) * Copyright (C) 2008 Red Hat, Inc. Steven Rostedt <srostedt@redhat.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) * Based on code by:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) * Ingo Molnar <mingo@redhat.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) * Guillaume Chazarain <guichaz@gmail.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) * What this file implements:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) * cpu_clock(i) provides a fast (execution time) high resolution
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) * clock with bounded drift between CPUs. The value of cpu_clock(i)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) * is monotonic for constant i. The timestamp returned is in nanoseconds.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) * ######################### BIG FAT WARNING ##########################
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) * # go backwards !! #
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) * ####################################################################
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) * There is no strict promise about the base, although it tends to start
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) * at 0 on boot (but people really shouldn't rely on that).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) * cpu_clock(i) -- can be used from any context, including NMI.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) * local_clock() -- is cpu_clock() on the current CPU.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * sched_clock_cpu(i)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) * How it is implemented:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * The implementation either uses sched_clock() when
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) * !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK, which means in that case the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * sched_clock() is assumed to provide these properties (mostly it means
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * the architecture provides a globally synchronized highres time source).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * Otherwise it tries to create a semi stable clock from a mixture of other
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) * clocks, including:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) * - GTOD (clock monotomic)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) * - sched_clock()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * - explicit idle events
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * We use GTOD as base and use sched_clock() deltas to improve resolution. The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * deltas are filtered to provide monotonicity and keeping it within an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * expected window.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) * Furthermore, explicit sleep and wakeup hooks allow us to account for time
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) * that is otherwise invisible (TSC gets stopped).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) #include "sched.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) #include <linux/sched_clock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * Scheduler clock - returns current time in nanosec units.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) * This is default implementation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) * Architectures and sub-architectures can override this.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) unsigned long long __weak sched_clock(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) return (unsigned long long)(jiffies - INITIAL_JIFFIES)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) * (NSEC_PER_SEC / HZ);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) EXPORT_SYMBOL_GPL(sched_clock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) static DEFINE_STATIC_KEY_FALSE(sched_clock_running);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) * We must start with !__sched_clock_stable because the unstable -> stable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) * transition is accurate, while the stable -> unstable transition is not.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * Similarly we start with __sched_clock_stable_early, thereby assuming we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) * will become stable, such that there's only a single 1 -> 0 transition.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) static int __sched_clock_stable_early = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) * We want: ktime_get_ns() + __gtod_offset == sched_clock() + __sched_clock_offset
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) __read_mostly u64 __sched_clock_offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) static __read_mostly u64 __gtod_offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) struct sched_clock_data {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) u64 tick_raw;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) u64 tick_gtod;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) u64 clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) static inline struct sched_clock_data *this_scd(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) return this_cpu_ptr(&sched_clock_data);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) static inline struct sched_clock_data *cpu_sdc(int cpu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) return &per_cpu(sched_clock_data, cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) int sched_clock_stable(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) return static_branch_likely(&__sched_clock_stable);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) static void __scd_stamp(struct sched_clock_data *scd)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) scd->tick_gtod = ktime_get_ns();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) scd->tick_raw = sched_clock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) static void __set_sched_clock_stable(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) struct sched_clock_data *scd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) * Since we're still unstable and the tick is already running, we have
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) * to disable IRQs in order to get a consistent scd->tick* reading.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) local_irq_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) scd = this_scd();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) * Attempt to make the (initial) unstable->stable transition continuous.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) __sched_clock_offset = (scd->tick_gtod + __gtod_offset) - (scd->tick_raw);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) local_irq_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) scd->tick_gtod, __gtod_offset,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) scd->tick_raw, __sched_clock_offset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) static_branch_enable(&__sched_clock_stable);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) * If we ever get here, we're screwed, because we found out -- typically after
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) * the fact -- that TSC wasn't good. This means all our clocksources (including
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * ktime) could have reported wrong values.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * What we do here is an attempt to fix up and continue sort of where we left
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) * off in a coherent manner.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * The only way to fully avoid random clock jumps is to boot with:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) * "tsc=unstable".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) static void __sched_clock_work(struct work_struct *work)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) struct sched_clock_data *scd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) int cpu;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) /* take a current timestamp and set 'now' */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) preempt_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) scd = this_scd();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) __scd_stamp(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) scd->clock = scd->tick_gtod + __gtod_offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) preempt_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) /* clone to all CPUs */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) for_each_possible_cpu(cpu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) per_cpu(sched_clock_data, cpu) = *scd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) printk(KERN_WARNING "TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) printk(KERN_INFO "sched_clock: Marking unstable (%lld, %lld)<-(%lld, %lld)\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) scd->tick_gtod, __gtod_offset,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) scd->tick_raw, __sched_clock_offset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) static_branch_disable(&__sched_clock_stable);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) static DECLARE_WORK(sched_clock_work, __sched_clock_work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) static void __clear_sched_clock_stable(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) if (!sched_clock_stable())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) schedule_work(&sched_clock_work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) void clear_sched_clock_stable(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) __sched_clock_stable_early = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) smp_mb(); /* matches sched_clock_init_late() */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) if (static_key_count(&sched_clock_running.key) == 2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) __clear_sched_clock_stable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) static void __sched_clock_gtod_offset(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) struct sched_clock_data *scd = this_scd();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) __scd_stamp(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) __gtod_offset = (scd->tick_raw + __sched_clock_offset) - scd->tick_gtod;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) void __init sched_clock_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) * Set __gtod_offset such that once we mark sched_clock_running,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) * sched_clock_tick() continues where sched_clock() left off.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) * Even if TSC is buggered, we're still UP at this point so it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) * can't really be out of sync.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) local_irq_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) __sched_clock_gtod_offset();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) local_irq_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) static_branch_inc(&sched_clock_running);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) * We run this as late_initcall() such that it runs after all built-in drivers,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) * notably: acpi_processor and intel_idle, which can mark the TSC as unstable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) static int __init sched_clock_init_late(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) static_branch_inc(&sched_clock_running);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) * Ensure that it is impossible to not do a static_key update.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) * Either {set,clear}_sched_clock_stable() must see sched_clock_running
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) * and do the update, or we must see their __sched_clock_stable_early
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) * and do the update, or both.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) smp_mb(); /* matches {set,clear}_sched_clock_stable() */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) if (__sched_clock_stable_early)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) __set_sched_clock_stable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) late_initcall(sched_clock_init_late);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) * min, max except they take wrapping into account
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) static inline u64 wrap_min(u64 x, u64 y)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) return (s64)(x - y) < 0 ? x : y;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) static inline u64 wrap_max(u64 x, u64 y)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) return (s64)(x - y) > 0 ? x : y;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) * update the percpu scd from the raw @now value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) * - filter out backward motion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) * - use the GTOD tick value to create a window to filter crazy TSC values
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) static u64 sched_clock_local(struct sched_clock_data *scd)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) u64 now, clock, old_clock, min_clock, max_clock, gtod;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) s64 delta;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) again:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) now = sched_clock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) delta = now - scd->tick_raw;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) if (unlikely(delta < 0))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) delta = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) old_clock = scd->clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) * scd->clock = clamp(scd->tick_gtod + delta,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) * max(scd->tick_gtod, scd->clock),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) * scd->tick_gtod + TICK_NSEC);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) gtod = scd->tick_gtod + __gtod_offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) clock = gtod + delta;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) min_clock = wrap_max(gtod, old_clock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) max_clock = wrap_max(old_clock, gtod + TICK_NSEC);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) clock = wrap_max(clock, min_clock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) clock = wrap_min(clock, max_clock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) goto again;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) return clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) static u64 sched_clock_remote(struct sched_clock_data *scd)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) struct sched_clock_data *my_scd = this_scd();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) u64 this_clock, remote_clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) u64 *ptr, old_val, val;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) #if BITS_PER_LONG != 64
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) again:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) * Careful here: The local and the remote clock values need to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) * be read out atomic as we need to compare the values and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) * then update either the local or the remote side. So the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) * cmpxchg64 below only protects one readout.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) * We must reread via sched_clock_local() in the retry case on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) * 32-bit kernels as an NMI could use sched_clock_local() via the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) * tracer and hit between the readout of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) * the low 32-bit and the high 32-bit portion.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) this_clock = sched_clock_local(my_scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) * We must enforce atomic readout on 32-bit, otherwise the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) * update on the remote CPU can hit inbetween the readout of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) * the low 32-bit and the high 32-bit portion.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) remote_clock = cmpxchg64(&scd->clock, 0, 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) * On 64-bit kernels the read of [my]scd->clock is atomic versus the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) * update, so we can avoid the above 32-bit dance.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) sched_clock_local(my_scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) again:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) this_clock = my_scd->clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) remote_clock = scd->clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) * Use the opportunity that we have both locks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) * taken to couple the two clocks: we take the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) * larger time as the latest time for both
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) * runqueues. (this creates monotonic movement)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) if (likely((s64)(remote_clock - this_clock) < 0)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) ptr = &scd->clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) old_val = remote_clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) val = this_clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) * Should be rare, but possible:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) ptr = &my_scd->clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) old_val = this_clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) val = remote_clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) if (cmpxchg64(ptr, old_val, val) != old_val)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) goto again;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) return val;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) * Similar to cpu_clock(), but requires local IRQs to be disabled.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) * See cpu_clock().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) u64 sched_clock_cpu(int cpu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) struct sched_clock_data *scd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) u64 clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) if (sched_clock_stable())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) return sched_clock() + __sched_clock_offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) if (!static_branch_likely(&sched_clock_running))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) return sched_clock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) preempt_disable_notrace();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) scd = cpu_sdc(cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) if (cpu != smp_processor_id())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) clock = sched_clock_remote(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) clock = sched_clock_local(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) preempt_enable_notrace();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) return clock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) EXPORT_SYMBOL_GPL(sched_clock_cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) void sched_clock_tick(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) struct sched_clock_data *scd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) if (sched_clock_stable())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) if (!static_branch_likely(&sched_clock_running))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) lockdep_assert_irqs_disabled();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) scd = this_scd();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) __scd_stamp(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) sched_clock_local(scd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) void sched_clock_tick_stable(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) if (!sched_clock_stable())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) * Called under watchdog_lock.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) * The watchdog just found this TSC to (still) be stable, so now is a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) * good moment to update our __gtod_offset. Because once we find the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) * TSC to be unstable, any computation will be computing crap.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) local_irq_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) __sched_clock_gtod_offset();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) local_irq_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) * We are going deep-idle (irqs are disabled):
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) void sched_clock_idle_sleep_event(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428) sched_clock_cpu(smp_processor_id());
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433) * We just idled; resync with ktime.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435) void sched_clock_idle_wakeup_event(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439) if (sched_clock_stable())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) if (unlikely(timekeeping_suspended))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446) sched_clock_tick();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) void __init sched_clock_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) static_branch_inc(&sched_clock_running);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) local_irq_disable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) generic_sched_clock_init();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) local_irq_enable();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) u64 sched_clock_cpu(int cpu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) if (!static_branch_likely(&sched_clock_running))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466) return sched_clock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) #endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472) * Running clock - returns the time that has elapsed while a guest has been
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) * running.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) * On a guest this value should be local_clock minus the time the guest was
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475) * suspended by the hypervisor (for any reason).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) * On bare metal this function should return the same as local_clock.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) * Architectures and sub-architectures can override this.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) u64 __weak running_clock(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481) return local_clock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482) }
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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