wrapper/trace-clock.h

   1 /*
   2  * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
   3  *
   4  * Contains LTTng trace clock mapping to LTTng trace clock or mainline monotonic
   5  * clock. This wrapper depends on CONFIG_HIGH_RES_TIMERS=y.
   6  *
   7  * Dual LGPL v2.1/GPL v2 license.
   8  */
   9
  10 #ifndef _LTTNG_TRACE_CLOCK_H
  11 #define _LTTNG_TRACE_CLOCK_H
  12
  13 #ifdef CONFIG_HAVE_TRACE_CLOCK
  14 #include <linux/trace-clock.h>
  15 #else /* CONFIG_HAVE_TRACE_CLOCK */
  16
  17 #include <linux/hardirq.h>
  18 #include <linux/ktime.h>
  19 #include <linux/time.h>
  20 #include <linux/hrtimer.h>
  21 #include "random.h"
  22
  23 static inline u64 trace_clock_monotonic_wrapper(void)
  24 {
  25         ktime_t ktime;
  26
  27         /*
  28          * Refuse to trace from NMIs with this wrapper, because an NMI could
  29          * nest over the xtime write seqlock and deadlock.
  30          */
  31         if (in_nmi())
  32                 return (u64) -EIO;
  33
  34         ktime = ktime_get();
  35         return (u64) ktime.tv64;
  36 }
  37
  38 static inline u32 trace_clock_read32(void)
  39 {
  40         return (u32) trace_clock_monotonic_wrapper();
  41 }
  42
  43 static inline u64 trace_clock_read64(void)
  44 {
  45         return (u64) trace_clock_monotonic_wrapper();
  46 }
  47
  48 static inline u64 trace_clock_freq(void)
  49 {
  50         return (u64) NSEC_PER_SEC;
  51 }
  52
  53 static inline int trace_clock_uuid(char *uuid)
  54 {
  55         return wrapper_get_bootid(uuid);
  56 }
  57
  58 static inline int get_trace_clock(void)
  59 {
  60         /*
  61          * LTTng: Using mainline kernel monotonic clock. NMIs will not be
  62          * traced, and expect significant performance degradation compared to
  63          * the LTTng trace clocks. Integration of the LTTng 0.x trace clocks
  64          * into LTTng 2.0 is planned in a near future.
  65          */
  66         printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock.\n");
  67         printk(KERN_WARNING "  * NMIs will not be traced,\n");
  68         printk(KERN_WARNING "  * expect significant performance degradation compared to the\n");
  69         printk(KERN_WARNING "    LTTng trace clocks.\n");
  70         printk(KERN_WARNING "Integration of the LTTng 0.x trace clocks into LTTng 2.0 is planned\n");
  71         printk(KERN_WARNING "in a near future.\n");
  72
  73         return 0;
  74 }
  75
  76 static inline void put_trace_clock(void)
  77 {
  78 }
  79
  80 #endif /* CONFIG_HAVE_TRACE_CLOCK */
  81
  82 #endif /* _LTTNG_TRACE_CLOCK_H */