| 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 _LTT_TRACE_CLOCK_H |
| 11 | #define _LTT_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 | |
| 22 | static inline u64 trace_clock_monotonic_wrapper(void) |
| 23 | { |
| 24 | ktime_t ktime; |
| 25 | |
| 26 | /* |
| 27 | * Refuse to trace from NMIs with this wrapper, because an NMI could |
| 28 | * nest over the xtime write seqlock and deadlock. |
| 29 | */ |
| 30 | if (in_nmi()) |
| 31 | return (u64) -EIO; |
| 32 | |
| 33 | ktime = ktime_get(); |
| 34 | return (u64) ktime.tv64; |
| 35 | } |
| 36 | |
| 37 | static inline u32 trace_clock_read32(void) |
| 38 | { |
| 39 | return (u32) trace_clock_monotonic_wrapper(); |
| 40 | } |
| 41 | |
| 42 | static inline u64 trace_clock_read64(void) |
| 43 | { |
| 44 | return (u64) trace_clock_monotonic_wrapper(); |
| 45 | } |
| 46 | |
| 47 | static inline u64 trace_clock_frequency(void) |
| 48 | { |
| 49 | return (u64)NSEC_PER_SEC; |
| 50 | } |
| 51 | |
| 52 | static inline u32 trace_clock_freq_scale(void) |
| 53 | { |
| 54 | return 1; |
| 55 | } |
| 56 | |
| 57 | static inline int get_trace_clock(void) |
| 58 | { |
| 59 | printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock.\n"); |
| 60 | printk(KERN_WARNING " * NMIs will not be traced,\n"); |
| 61 | printk(KERN_WARNING " * expect significant performance degradation compared to the\n"); |
| 62 | printk(KERN_WARNING " LTTng trace clocks.\n"); |
| 63 | printk(KERN_WARNING "You should consider deploying a kernel with the the LTTng kernel\n"); |
| 64 | printk(KERN_WARNING "patches, or, better, ask the Linux tracing maintainers to integrate\n"); |
| 65 | printk(KERN_WARNING "them if you care deeply about this.\n"); |
| 66 | |
| 67 | #warning "LTTng: Using mainline kernel monotonic clock. NMIs will not be traced, and expect significant performance degradation compared to the LTTng trace clocks. You should consider deploying a kernel with the the LTTng kernel patches, or, better, ask the Linux tracing maintainers to integrate them if you care deeply about this." |
| 68 | |
| 69 | return 0; |
| 70 | } |
| 71 | |
| 72 | static inline void put_trace_clock(void) |
| 73 | { |
| 74 | } |
| 75 | |
| 76 | #endif /* CONFIG_HAVE_TRACE_CLOCK */ |
| 77 | |
| 78 | #endif /* _LTT_TRACE_CLOCK_H */ |