X86 LTTng timestamping. Depends on ltt-test-tsc module to detect if timestamp counters are synchronized on the machine. Signed-off-by: Mathieu Desnoyers CC: Thomas Gleixner CC: Ingo Molnar CC: H. Peter Anvin CC: Linus Torvalds CC: Andrew Morton CC: Peter Zijlstra CC: Steven Rostedt --- arch/x86/Kconfig | 2 include/asm-x86/ltt.h | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 125 insertions(+) Index: linux-2.6-lttng/include/asm-x86/ltt.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6-lttng/include/asm-x86/ltt.h 2008-10-16 18:53:27.000000000 -0400 @@ -0,0 +1,123 @@ +#ifndef _ASM_X86_LTT_H +#define _ASM_X86_LTT_H +/* + * linux/include/asm-x86/ltt.h + * + * Copyright (C) 2005,2006 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) + * + * x86 time and TSC definitions for ltt + */ + +#include +#include +#include +#include + +/* Minimum duration of a probe, in cycles */ +#define LTT_MIN_PROBE_DURATION 200 + +#ifdef CONFIG_HAVE_LTT_SYNTHETIC_TSC +/* Only for testing. Never needed on x86. */ +u64 ltt_read_synthetic_tsc(void); +#endif + +#ifdef CONFIG_HAVE_LTT_UNSTABLE_TSC +extern cycles_t ltt_last_tsc; +extern int ltt_tsc_is_sync; + +/* + * Support for architectures with non-sync TSCs. + * When the local TSC is discovered to lag behind the highest TSC counter, we + * increment the TSC count of an amount that should be, ideally, lower than the + * execution time of this routine, in cycles : this is the granularity we look + * for : we must be able to order the events. + */ +static inline cycles_t ltt_async_tsc_read(void) +{ + cycles_t new_tsc; + cycles_t last_tsc; + + rdtsc_barrier(); + new_tsc = get_cycles(); + rdtsc_barrier(); + do { + last_tsc = ltt_last_tsc; + if (new_tsc < last_tsc) + new_tsc = last_tsc + LTT_MIN_PROBE_DURATION; + /* + * If cmpxchg fails with a value higher than the new_tsc, don't + * retry : the value has been incremented and the events + * happened almost at the same time. + * We must retry if cmpxchg fails with a lower value : + * it means that we are the CPU with highest frequency and + * therefore MUST update the value. + */ + } while (cmpxchg64(<t_last_tsc, last_tsc, new_tsc) < new_tsc); + return new_tsc; +} + +static inline u32 ltt_get_timestamp32(void) +{ + u32 cycles; + + if (ltt_tsc_is_sync) { + rdtsc_barrier(); + cycles = (u32)get_cycles(); /* only need the 32 LSB */ + rdtsc_barrier(); + } else + cycles = (u32)ltt_async_tsc_read(); + return cycles; +} + +static inline u64 ltt_get_timestamp64(void) +{ + u64 cycles; + + if (ltt_tsc_is_sync) { + rdtsc_barrier(); + cycles = get_cycles(); + rdtsc_barrier(); + } else + cycles = ltt_async_tsc_read(); + return cycles; +} +#else /* CONFIG_HAVE_LTT_UNSTABLE_TSC */ +static inline u32 ltt_get_timestamp32(void) +{ + u32 cycles; + + rdtsc_barrier(); + cycles = (u32)get_cycles(); /* only need the 32 LSB */ + rdtsc_barrier(); + return cycles; +} + +static inline u64 ltt_get_timestamp64(void) +{ + u64 cycles; + + rdtsc_barrier(); + cycles = get_cycles(); + rdtsc_barrier(); + return cycles; +} +#endif /* CONFIG_HAVE_LTT_UNSTABLE_TSC */ + +/* + * Periodic IPI to have an upper bound on TSC inaccuracy. + * TODO: should implement this in ltt-test-tsc.ko. + */ +static inline void ltt_add_timestamp(unsigned long ticks) +{ } + +static inline unsigned int ltt_frequency(void) +{ + return cpu_khz; +} + +static inline u32 ltt_freq_scale(void) +{ + return 1000; +} + +#endif /* _ASM_X86_LTT_H */ Index: linux-2.6-lttng/arch/x86/Kconfig =================================================================== --- linux-2.6-lttng.orig/arch/x86/Kconfig 2008-10-16 18:50:29.000000000 -0400 +++ linux-2.6-lttng/arch/x86/Kconfig 2008-10-16 18:53:09.000000000 -0400 @@ -26,6 +26,8 @@ config X86 select HAVE_KPROBES select ARCH_WANT_OPTIONAL_GPIOLIB select HAVE_KRETPROBES + select HAVE_LTT_CLOCK + select HAVE_LTT_UNSTABLE_TSC select HAVE_DYNAMIC_FTRACE select HAVE_FTRACE select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64) -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/