Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 1 | /* |
| 2 | * sched_clock for unstable cpu clocks |
| 3 | * |
| 4 | * Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
| 5 | * |
Steven Rostedt | c300ba2 | 2008-07-09 00:15:33 -0400 | [diff] [blame] | 6 | * Updates and enhancements: |
| 7 | * Copyright (C) 2008 Red Hat, Inc. Steven Rostedt <srostedt@redhat.com> |
| 8 | * |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 9 | * Based on code by: |
| 10 | * Ingo Molnar <mingo@redhat.com> |
| 11 | * Guillaume Chazarain <guichaz@gmail.com> |
| 12 | * |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 13 | * |
| 14 | * What: |
| 15 | * |
| 16 | * cpu_clock(i) provides a fast (execution time) high resolution |
| 17 | * clock with bounded drift between CPUs. The value of cpu_clock(i) |
| 18 | * is monotonic for constant i. The timestamp returned is in nanoseconds. |
| 19 | * |
| 20 | * ######################### BIG FAT WARNING ########################## |
| 21 | * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can # |
| 22 | * # go backwards !! # |
| 23 | * #################################################################### |
| 24 | * |
| 25 | * There is no strict promise about the base, although it tends to start |
| 26 | * at 0 on boot (but people really shouldn't rely on that). |
| 27 | * |
| 28 | * cpu_clock(i) -- can be used from any context, including NMI. |
| 29 | * sched_clock_cpu(i) -- must be used with local IRQs disabled (implied by NMI) |
| 30 | * local_clock() -- is cpu_clock() on the current cpu. |
| 31 | * |
| 32 | * How: |
| 33 | * |
| 34 | * The implementation either uses sched_clock() when |
| 35 | * !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK, which means in that case the |
| 36 | * sched_clock() is assumed to provide these properties (mostly it means |
| 37 | * the architecture provides a globally synchronized highres time source). |
| 38 | * |
| 39 | * Otherwise it tries to create a semi stable clock from a mixture of other |
| 40 | * clocks, including: |
| 41 | * |
| 42 | * - GTOD (clock monotomic) |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 43 | * - sched_clock() |
| 44 | * - explicit idle events |
| 45 | * |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 46 | * We use GTOD as base and use sched_clock() deltas to improve resolution. The |
| 47 | * deltas are filtered to provide monotonicity and keeping it within an |
| 48 | * expected window. |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 49 | * |
| 50 | * Furthermore, explicit sleep and wakeup hooks allow us to account for time |
| 51 | * that is otherwise invisible (TSC gets stopped). |
| 52 | * |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 53 | * |
| 54 | * Notes: |
| 55 | * |
| 56 | * The !IRQ-safetly of sched_clock() and sched_clock_cpu() comes from things |
| 57 | * like cpufreq interrupts that can change the base clock (TSC) multiplier |
| 58 | * and cause funny jumps in time -- although the filtering provided by |
| 59 | * sched_clock_cpu() should mitigate serious artifacts we cannot rely on it |
| 60 | * in general since for !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK we fully rely on |
| 61 | * sched_clock(). |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 62 | */ |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 63 | #include <linux/spinlock.h> |
Ingo Molnar | 6409c4d | 2008-05-12 21:21:14 +0200 | [diff] [blame] | 64 | #include <linux/hardirq.h> |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 65 | #include <linux/module.h> |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 66 | #include <linux/percpu.h> |
| 67 | #include <linux/ktime.h> |
| 68 | #include <linux/sched.h> |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 69 | |
Hugh Dickins | 2c3d103 | 2008-07-25 19:45:00 +0100 | [diff] [blame] | 70 | /* |
| 71 | * Scheduler clock - returns current time in nanosec units. |
| 72 | * This is default implementation. |
| 73 | * Architectures and sub-architectures can override this. |
| 74 | */ |
| 75 | unsigned long long __attribute__((weak)) sched_clock(void) |
| 76 | { |
Ron | 92d23f7 | 2009-05-08 22:54:49 +0930 | [diff] [blame] | 77 | return (unsigned long long)(jiffies - INITIAL_JIFFIES) |
| 78 | * (NSEC_PER_SEC / HZ); |
Hugh Dickins | 2c3d103 | 2008-07-25 19:45:00 +0100 | [diff] [blame] | 79 | } |
Divyesh Shah | b6ac23af | 2010-04-15 08:54:59 +0200 | [diff] [blame] | 80 | EXPORT_SYMBOL_GPL(sched_clock); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 81 | |
Peter Zijlstra | c1955a3 | 2008-08-11 08:59:03 +0200 | [diff] [blame] | 82 | static __read_mostly int sched_clock_running; |
| 83 | |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 84 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 85 | __read_mostly int sched_clock_stable; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 86 | |
| 87 | struct sched_clock_data { |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 88 | u64 tick_raw; |
| 89 | u64 tick_gtod; |
| 90 | u64 clock; |
| 91 | }; |
| 92 | |
| 93 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data); |
| 94 | |
| 95 | static inline struct sched_clock_data *this_scd(void) |
| 96 | { |
| 97 | return &__get_cpu_var(sched_clock_data); |
| 98 | } |
| 99 | |
| 100 | static inline struct sched_clock_data *cpu_sdc(int cpu) |
| 101 | { |
| 102 | return &per_cpu(sched_clock_data, cpu); |
| 103 | } |
| 104 | |
| 105 | void sched_clock_init(void) |
| 106 | { |
| 107 | u64 ktime_now = ktime_to_ns(ktime_get()); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 108 | int cpu; |
| 109 | |
| 110 | for_each_possible_cpu(cpu) { |
| 111 | struct sched_clock_data *scd = cpu_sdc(cpu); |
| 112 | |
Peter Zijlstra | a381759 | 2008-05-29 10:07:15 +0200 | [diff] [blame] | 113 | scd->tick_raw = 0; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 114 | scd->tick_gtod = ktime_now; |
| 115 | scd->clock = ktime_now; |
| 116 | } |
Peter Zijlstra | a381759 | 2008-05-29 10:07:15 +0200 | [diff] [blame] | 117 | |
| 118 | sched_clock_running = 1; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 119 | } |
| 120 | |
| 121 | /* |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 122 | * min, max except they take wrapping into account |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 123 | */ |
| 124 | |
| 125 | static inline u64 wrap_min(u64 x, u64 y) |
| 126 | { |
| 127 | return (s64)(x - y) < 0 ? x : y; |
| 128 | } |
| 129 | |
| 130 | static inline u64 wrap_max(u64 x, u64 y) |
| 131 | { |
| 132 | return (s64)(x - y) > 0 ? x : y; |
| 133 | } |
| 134 | |
| 135 | /* |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 136 | * update the percpu scd from the raw @now value |
| 137 | * |
| 138 | * - filter out backward motion |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 139 | * - use the GTOD tick value to create a window to filter crazy TSC values |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 140 | */ |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 141 | static u64 sched_clock_local(struct sched_clock_data *scd) |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 142 | { |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 143 | u64 now, clock, old_clock, min_clock, max_clock; |
| 144 | s64 delta; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 145 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 146 | again: |
| 147 | now = sched_clock(); |
| 148 | delta = now - scd->tick_raw; |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 149 | if (unlikely(delta < 0)) |
| 150 | delta = 0; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 151 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 152 | old_clock = scd->clock; |
| 153 | |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 154 | /* |
| 155 | * scd->clock = clamp(scd->tick_gtod + delta, |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 156 | * max(scd->tick_gtod, scd->clock), |
| 157 | * scd->tick_gtod + TICK_NSEC); |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 158 | */ |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 159 | |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 160 | clock = scd->tick_gtod + delta; |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 161 | min_clock = wrap_max(scd->tick_gtod, old_clock); |
| 162 | max_clock = wrap_max(old_clock, scd->tick_gtod + TICK_NSEC); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 163 | |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 164 | clock = wrap_max(clock, min_clock); |
| 165 | clock = wrap_min(clock, max_clock); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 166 | |
Eric Dumazet | 152f9d0 | 2009-09-30 20:36:19 +0200 | [diff] [blame] | 167 | if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock) |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 168 | goto again; |
Ingo Molnar | 56b9061 | 2008-07-30 10:15:55 +0200 | [diff] [blame] | 169 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 170 | return clock; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 171 | } |
| 172 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 173 | static u64 sched_clock_remote(struct sched_clock_data *scd) |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 174 | { |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 175 | struct sched_clock_data *my_scd = this_scd(); |
| 176 | u64 this_clock, remote_clock; |
| 177 | u64 *ptr, old_val, val; |
| 178 | |
| 179 | sched_clock_local(my_scd); |
| 180 | again: |
| 181 | this_clock = my_scd->clock; |
| 182 | remote_clock = scd->clock; |
| 183 | |
| 184 | /* |
| 185 | * Use the opportunity that we have both locks |
| 186 | * taken to couple the two clocks: we take the |
| 187 | * larger time as the latest time for both |
| 188 | * runqueues. (this creates monotonic movement) |
| 189 | */ |
| 190 | if (likely((s64)(remote_clock - this_clock) < 0)) { |
| 191 | ptr = &scd->clock; |
| 192 | old_val = remote_clock; |
| 193 | val = this_clock; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 194 | } else { |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 195 | /* |
| 196 | * Should be rare, but possible: |
| 197 | */ |
| 198 | ptr = &my_scd->clock; |
| 199 | old_val = this_clock; |
| 200 | val = remote_clock; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 201 | } |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 202 | |
Eric Dumazet | 152f9d0 | 2009-09-30 20:36:19 +0200 | [diff] [blame] | 203 | if (cmpxchg64(ptr, old_val, val) != old_val) |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 204 | goto again; |
| 205 | |
| 206 | return val; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 207 | } |
| 208 | |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 209 | /* |
| 210 | * Similar to cpu_clock(), but requires local IRQs to be disabled. |
| 211 | * |
| 212 | * See cpu_clock(). |
| 213 | */ |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 214 | u64 sched_clock_cpu(int cpu) |
| 215 | { |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 216 | struct sched_clock_data *scd; |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 217 | u64 clock; |
| 218 | |
| 219 | WARN_ON_ONCE(!irqs_disabled()); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 220 | |
Ingo Molnar | b342501 | 2009-02-26 20:20:29 +0100 | [diff] [blame] | 221 | if (sched_clock_stable) |
| 222 | return sched_clock(); |
Peter Zijlstra | a381759 | 2008-05-29 10:07:15 +0200 | [diff] [blame] | 223 | |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 224 | if (unlikely(!sched_clock_running)) |
| 225 | return 0ull; |
| 226 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 227 | scd = cpu_sdc(cpu); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 228 | |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 229 | if (cpu != smp_processor_id()) |
| 230 | clock = sched_clock_remote(scd); |
| 231 | else |
| 232 | clock = sched_clock_local(scd); |
Ingo Molnar | e4e4e53 | 2008-04-14 08:50:02 +0200 | [diff] [blame] | 233 | |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 234 | return clock; |
| 235 | } |
| 236 | |
| 237 | void sched_clock_tick(void) |
| 238 | { |
Peter Zijlstra | 8325d9c | 2009-02-26 21:40:16 +0100 | [diff] [blame] | 239 | struct sched_clock_data *scd; |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 240 | u64 now, now_gtod; |
| 241 | |
Peter Zijlstra | 8325d9c | 2009-02-26 21:40:16 +0100 | [diff] [blame] | 242 | if (sched_clock_stable) |
| 243 | return; |
| 244 | |
Peter Zijlstra | a381759 | 2008-05-29 10:07:15 +0200 | [diff] [blame] | 245 | if (unlikely(!sched_clock_running)) |
| 246 | return; |
| 247 | |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 248 | WARN_ON_ONCE(!irqs_disabled()); |
| 249 | |
Peter Zijlstra | 8325d9c | 2009-02-26 21:40:16 +0100 | [diff] [blame] | 250 | scd = this_scd(); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 251 | now_gtod = ktime_to_ns(ktime_get()); |
Steven Rostedt | a83bc47 | 2008-07-09 00:15:32 -0400 | [diff] [blame] | 252 | now = sched_clock(); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 253 | |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 254 | scd->tick_raw = now; |
| 255 | scd->tick_gtod = now_gtod; |
Peter Zijlstra | def0a9b | 2009-09-18 20:14:01 +0200 | [diff] [blame] | 256 | sched_clock_local(scd); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 257 | } |
| 258 | |
| 259 | /* |
| 260 | * We are going deep-idle (irqs are disabled): |
| 261 | */ |
| 262 | void sched_clock_idle_sleep_event(void) |
| 263 | { |
| 264 | sched_clock_cpu(smp_processor_id()); |
| 265 | } |
| 266 | EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event); |
| 267 | |
| 268 | /* |
| 269 | * We just idled delta nanoseconds (called with irqs disabled): |
| 270 | */ |
| 271 | void sched_clock_idle_wakeup_event(u64 delta_ns) |
| 272 | { |
Thomas Gleixner | 1c5745a | 2008-12-22 23:05:28 +0100 | [diff] [blame] | 273 | if (timekeeping_suspended) |
| 274 | return; |
| 275 | |
Peter Zijlstra | 354879b | 2008-08-25 17:15:34 +0200 | [diff] [blame] | 276 | sched_clock_tick(); |
Peter Zijlstra | 3e51f33 | 2008-05-03 18:29:28 +0200 | [diff] [blame] | 277 | touch_softlockup_watchdog(); |
| 278 | } |
| 279 | EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); |
| 280 | |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 281 | /* |
| 282 | * As outlined at the top, provides a fast, high resolution, nanosecond |
| 283 | * time source that is monotonic per cpu argument and has bounded drift |
| 284 | * between cpus. |
| 285 | * |
| 286 | * ######################### BIG FAT WARNING ########################## |
| 287 | * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can # |
| 288 | * # go backwards !! # |
| 289 | * #################################################################### |
| 290 | */ |
| 291 | u64 cpu_clock(int cpu) |
David Miller | b9f8fcd | 2009-12-13 18:25:02 -0800 | [diff] [blame] | 292 | { |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 293 | u64 clock; |
David Miller | b9f8fcd | 2009-12-13 18:25:02 -0800 | [diff] [blame] | 294 | unsigned long flags; |
| 295 | |
| 296 | local_irq_save(flags); |
| 297 | clock = sched_clock_cpu(cpu); |
| 298 | local_irq_restore(flags); |
| 299 | |
| 300 | return clock; |
| 301 | } |
| 302 | |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 303 | /* |
| 304 | * Similar to cpu_clock() for the current cpu. Time will only be observed |
| 305 | * to be monotonic if care is taken to only compare timestampt taken on the |
| 306 | * same CPU. |
| 307 | * |
| 308 | * See cpu_clock(). |
| 309 | */ |
| 310 | u64 local_clock(void) |
| 311 | { |
| 312 | u64 clock; |
| 313 | unsigned long flags; |
| 314 | |
| 315 | local_irq_save(flags); |
| 316 | clock = sched_clock_cpu(smp_processor_id()); |
| 317 | local_irq_restore(flags); |
| 318 | |
| 319 | return clock; |
| 320 | } |
| 321 | |
Peter Zijlstra | 8325d9c | 2009-02-26 21:40:16 +0100 | [diff] [blame] | 322 | #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ |
| 323 | |
| 324 | void sched_clock_init(void) |
| 325 | { |
| 326 | sched_clock_running = 1; |
| 327 | } |
| 328 | |
| 329 | u64 sched_clock_cpu(int cpu) |
| 330 | { |
| 331 | if (unlikely(!sched_clock_running)) |
| 332 | return 0; |
| 333 | |
| 334 | return sched_clock(); |
| 335 | } |
| 336 | |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 337 | u64 cpu_clock(int cpu) |
Peter Zijlstra | 76a2a6e | 2008-06-27 13:41:15 +0200 | [diff] [blame] | 338 | { |
David Miller | b9f8fcd | 2009-12-13 18:25:02 -0800 | [diff] [blame] | 339 | return sched_clock_cpu(cpu); |
Peter Zijlstra | 76a2a6e | 2008-06-27 13:41:15 +0200 | [diff] [blame] | 340 | } |
David Miller | b9f8fcd | 2009-12-13 18:25:02 -0800 | [diff] [blame] | 341 | |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 342 | u64 local_clock(void) |
| 343 | { |
| 344 | return sched_clock_cpu(0); |
| 345 | } |
| 346 | |
David Miller | b9f8fcd | 2009-12-13 18:25:02 -0800 | [diff] [blame] | 347 | #endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ |
| 348 | |
Ingo Molnar | 4c9fe8a | 2008-06-27 14:49:35 +0200 | [diff] [blame] | 349 | EXPORT_SYMBOL_GPL(cpu_clock); |
Peter Zijlstra | c676329 | 2010-05-25 10:48:51 +0200 | [diff] [blame] | 350 | EXPORT_SYMBOL_GPL(local_clock); |