[ltt-dev] [PATCH] We now rely on the lib userspace rcu API for the trace_clock_read64 function that will now use get_cycles which is architecture _aware_

[ltt-dev] [PATCH] We now rely on the lib userspace rcu API for the trace_clock_read64 function that will now use get_cycles which is architecture _aware_

[Mathieu Desnoyers]

* David Goulet (david.goulet at polymtl.ca) wrote:
> ---
>  include/ust/clock.h |   72 +++++----------------------------------------------
>  1 files changed, 7 insertions(+), 65 deletions(-)
> 
> diff --git a/include/ust/clock.h b/include/ust/clock.h
> index cb8a663..27279b6 100644
> --- a/include/ust/clock.h
> +++ b/include/ust/clock.h
> @@ -18,8 +18,6 @@
>  #ifndef UST_CLOCK_H
>  #define UST_CLOCK_H
>  
> -#include <time.h>
> -#include <sys/time.h>
>  #include <ust/kcompat/kcompat.h>
>  
>  /* TRACE CLOCK */
> @@ -35,77 +33,21 @@
>     For merging traces with the kernel, a time source compatible with that of
>     the kernel is necessary.
>  
> -   Instead of gettimeofday(), we are now using clock_gettime for better
> -   precision and monotonicity.
> -
> +   We now use the lib userspace RCU API for clock read.

Hrm, have you checked if get_cycles() is still in the userspace RCU
library git master ? I think we removed it from the standard API.

Mathieu

>  */
>  
> -#define TRACE_CLOCK_GENERIC
> -#ifdef TRACE_CLOCK_GENERIC
> -
> -static __inline__ u64 trace_clock_read64(void)
> -{
> -	struct timespec ts;
> -	u64 retval;
> -
> -	clock_gettime(CLOCK_MONOTONIC, &ts);
> -	retval = ts.tv_sec;
> -	retval *= 1000000000;
> -	retval += ts.tv_nsec;
> -
> -	return retval;
> -}
> -
> -#else
> -
> -#if __i386 || __x86_64
> -
> -/* 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.
> +/*
> + * Generic trace_clock_read64 function
>   */
>  static __inline__ u64 trace_clock_read64(void)
>  {
> -	uint32_t low;
> -	uint32_t high;
> -	uint64_t retval;
> -	__asm__ volatile ("rdtsc\n" : "=a" (low), "=d" (high));
> +	cycles_t retval;
>  
> -	retval = high;
> -	retval <<= 32;
> -	return retval | low;
> +	/* Lib urcu API for cycles count */
> +	retval = get_cycles();
> +	return (u64)retval;
>  }
>  
> -#endif /* __i386 || __x86_64 */
> -
> -#ifdef __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;
> -}
> -
> -#endif /* __PPC__ */
> -
> -#endif /* ! UST_TRACE_CLOCK_GENERIC */
> -
>  static __inline__ u64 trace_clock_frequency(void)
>  {
>  	return 1000000000LL;
> -- 
> 1.7.0.4
> 
> 
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> ltt-dev at lists.casi.polymtl.ca
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> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com