[ltt-dev] [UST PATCH] Add LTTng clock source support

[David Goulet]

Ignore! ... Format is bad

Resend in a jiffy

David

On 11-01-11 10:43 AM, David Goulet wrote:
> From: Julien Desfossez<julien.desfossez at polymtl.ca>
>
> At runtime, UST checks if the LTTng clock source is available
> If not, CLOCK_MONOTONIC is the default fallback.
>
> This makes UST use the LTTng kernel clock source. With this
> clock support, LTTng and UST traces are perfectly synchronize.
> Traces from these two tracer can be merge for analysis.
>
> LTTng 0.240 or higher is needed for this new clock source.
>
> Signed-off-by: David Goulet<david.goulet at polymtl.ca>
> ---
>   include/ust/clock.h |  116 ++++++++++++++++++++++++++------------------------
>   libust/tracectl.c   |   10 ++++
>   2 files changed, 70 insertions(+), 56 deletions(-)
>
> diff --git a/include/ust/clock.h b/include/ust/clock.h
> index cb8a663..27e0347 100644
> --- a/include/ust/clock.h
> +++ b/include/ust/clock.h
> @@ -15,8 +15,8 @@
>    * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
>    */
>
> -#ifndef UST_CLOCK_H
> -#define UST_CLOCK_H
> +#ifndef _UST_CLOCK_H
> +#define _UST_CLOCK_H
>
>   #include<time.h>
>   #include<sys/time.h>
> @@ -37,78 +37,82 @@
>
>      Instead of gettimeofday(), we are now using clock_gettime for better
>      precision and monotonicity.
> -
>   */
>
> -#define TRACE_CLOCK_GENERIC
> -#ifdef TRACE_CLOCK_GENERIC
> -
> -static __inline__ u64 trace_clock_read64(void)
> -{
> +#if __i386__ || __x86_64__
> +/* Only available for x86 arch */
> +#define CLOCK_TRACE_FREQ  14
> +#define CLOCK_TRACE  15
> +union lttng_timespec {
>   	struct timespec ts;
> -	u64 retval;
> -
> -	clock_gettime(CLOCK_MONOTONIC,&ts);
> -	retval = ts.tv_sec;
> -	retval *= 1000000000;
> -	retval += ts.tv_nsec;
> -
> -	return retval;
> -}
> -
> -#else
> +	u64 lttng_ts;
> +};
> +#endif /* __i386__ || __x86_64__ */
>
> -#if __i386 || __x86_64
> +static int ust_clock_source;
>
> -/* WARNING: Make sure to set frequency and scaling functions that will not
> - * result in lttv timestamps (sec.nsec) with seconds greater than 2**32-1.
> - */
> +/* Choosing correct trace clock */
> +#if __PPC__
>   static __inline__ u64 trace_clock_read64(void)
>   {
> -	uint32_t low;
> -	uint32_t high;
> -	uint64_t retval;
> -	__asm__ volatile ("rdtsc\n" : "=a" (low), "=d" (high));
> -
> -	retval = high;
> -	retval<<= 32;
> -	return retval | low;
> +    unsigned long tb_l;
> +    unsigned long tb_h;
> +    unsigned long tb_h2;
> +    u64 tb;
> +
> +    __asm__ (
> +            "1:\n\t"
> +            "mftbu %[rhigh]\n\t"
> +            "mftb %[rlow]\n\t"
> +            "mftbu %[rhigh2]\n\t"
> +            "cmpw %[rhigh],%[rhigh2]\n\t"
> +            "bne 1b\n\t"
> +            : [rhigh] "=r" (tb_h), [rhigh2] "=r" (tb_h2), [rlow] "=r" (tb_l));
> +
> +    tb = tb_h;
> +    tb<<= 32;
> +    tb |= tb_l;
> +
> +    return tb;
>   }
>
> -#endif /* __i386 || __x86_64 */
> -
> -#ifdef __PPC__
> +#else   /* !__PPC__ */
>
>   static __inline__ u64 trace_clock_read64(void)
>   {
> -	unsigned long tb_l;
> -	unsigned long tb_h;
> -	unsigned long tb_h2;
> -	u64 tb;
> -
> -	__asm__ (
> -		"1:\n\t"
> -		"mftbu %[rhigh]\n\t"
> -		"mftb %[rlow]\n\t"
> -		"mftbu %[rhigh2]\n\t"
> -		"cmpw %[rhigh],%[rhigh2]\n\t"
> -		"bne 1b\n\t"
> -	: [rhigh] "=r" (tb_h), [rhigh2] "=r" (tb_h2), [rlow] "=r" (tb_l));
> -	
> -	tb = tb_h;
> -	tb<<= 32;
> -	tb |= tb_l;
> -
> -	return tb;
> +	struct timespec ts;
> +	u64 retval;
> +	union lttng_timespec *lts = (union lttng_timespec *)&ts;
> +
> +	clock_gettime(ust_clock_source,&ts);
> +	/*
> +	 * Clock source can change when loading the binary (tracectl.c)
> +	 * so we must check if the clock source has changed before
> +	 * returning the correct value
> +	 */
> +	if(likely(ust_clock_source == CLOCK_TRACE)) {
> +		retval = lts->lttng_ts;
> +	} else { /* CLOCK_MONOTONIC */
> +		retval = ts.tv_sec;
> +		retval *= 1000000000;
> +		retval += ts.tv_nsec;
> +	}
> +
> +	return retval;
>   }
>
>   #endif /* __PPC__ */
>
> -#endif /* ! UST_TRACE_CLOCK_GENERIC */
> -
>   static __inline__ u64 trace_clock_frequency(void)
>   {
> -	return 1000000000LL;
> +	struct timespec ts;
> +	union lttng_timespec *lts = (union lttng_timespec *)&ts;
> +
> +	if(likely(ust_clock_source == CLOCK_TRACE)) {
> +		clock_gettime(CLOCK_TRACE_FREQ,&ts);
> +		return lts->lttng_ts;
> +	}
> +    return 1000000000LL;
>   }
>
>   static __inline__ u32 trace_clock_freq_scale(void)
> diff --git a/libust/tracectl.c b/libust/tracectl.c
> index b783c76..f6d9ea1 100644
> --- a/libust/tracectl.c
> +++ b/libust/tracectl.c
> @@ -39,6 +39,7 @@
>   #include<ust/marker.h>
>   #include<ust/tracepoint.h>
>   #include<ust/tracectl.h>
> +#include<ust/clock.h>
>   #include "tracer.h"
>   #include "usterr.h"
>   #include "ustcomm.h"
> @@ -1262,6 +1263,15 @@ static void __attribute__((constructor)) init()
>
>   	create_listener();
>
> +    /* Get clock the clock source type */
> +    struct timespec ts;
> +	/* Default clock source */
> +	ust_clock_source = CLOCK_TRACE;
> +    if(clock_gettime(ust_clock_source,&ts) != 0) {
> +        ust_clock_source = CLOCK_MONOTONIC;
> +        WARN("UST traces will not be synchronized with LTTng traces");
> +    }
> +
>   	autoprobe_val = getenv("UST_AUTOPROBE");
>   	if (autoprobe_val) {
>   		struct marker_iter iter;

-- 
David Goulet
LTTng project, DORSAL Lab.

PGP/GPG : 1024D/16BD8563
BE3C 672B 9331 9796 291A  14C6 4AF7 C14B 16BD 8563