From c34bb0dcfa8ba1294cd5182349e1ddbe34f81bf4 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Wed, 13 Jun 2012 11:39:43 +0200 Subject: score: Fix performance issue for 64-bit timestamps The 64-bit timestamps were introduced to simplify the timestamp calculations. This works well since nearly all operations are additions. The previous _TOD_Tickle_ticks() implementation had a serious performance regression in case of 64-bit timestamps due to the usage of two 64-bit divisions which are quite expensive on some architectures. A new field seconds_trigger in TOD_Control is introduced to trigger the _Watchdog_Tickle_seconds() in _TOD_Tickle_ticks(). This avoids the 64-bit divisions completely and only 32-bit additions are used. --- cpukit/score/include/rtems/score/timestamp.h | 25 --------------------- cpukit/score/include/rtems/score/timestamp64.h | 30 -------------------------- cpukit/score/include/rtems/score/tod.h | 9 ++++++++ cpukit/score/src/coretodset.c | 2 ++ cpukit/score/src/coretodtickle.c | 18 ++++++++++------ 5 files changed, 22 insertions(+), 62 deletions(-) diff --git a/cpukit/score/include/rtems/score/timestamp.h b/cpukit/score/include/rtems/score/timestamp.h index b86090978e..83948b46e1 100644 --- a/cpukit/score/include/rtems/score/timestamp.h +++ b/cpukit/score/include/rtems/score/timestamp.h @@ -193,31 +193,6 @@ extern "C" { _Timestamp64_Add_to( _time, _add ) #endif -/** - * @brief Add to a Timestamp (At Clock Tick) - * - * This routine adds two timestamps. The second argument is added - * to the first. - * - * @node This routine places a special requirement on the addition - * operation. It must return the number of units that the - * seconds field changed as the result of the addition. Since this - * operation is ONLY used as part of processing a clock tick, - * it is generally safe to assume that only one second changed. - * - * @param[in] _time points to the base time to be added to - * @param[in] _add points to the timestamp to add to the first argument - * - * @return This method returns the number of seconds @a time increased by. - */ -#if CPU_TIMESTAMP_USE_STRUCT_TIMESPEC == TRUE - #define _Timestamp_Add_to_at_tick( _time, _add ) \ - _Timespec_Add_to( _time, _add ) -#else - #define _Timestamp_Add_to_at_tick( _time, _add ) \ - _Timestamp64_Add_to_at_tick( _time, _add ) -#endif - /** * @brief Convert Timestamp to Number of Ticks * diff --git a/cpukit/score/include/rtems/score/timestamp64.h b/cpukit/score/include/rtems/score/timestamp64.h index 08d3ac7ecd..1c1ea2c90c 100644 --- a/cpukit/score/include/rtems/score/timestamp64.h +++ b/cpukit/score/include/rtems/score/timestamp64.h @@ -208,36 +208,6 @@ static inline void _Timestamp64_implementation_Add_to( ); #endif -/** - * @brief Add to a Timestamp (At Clock Tick) - * - * This routine adds two timestamps. The second argument is added - * to the first. - * - * @node This routine places a special requirement on the addition - * operation. It must return the number of units that the - * seconds field changed as the result of the addition. Since this - * operation is ONLY used as part of processing a clock tick, - * it is generally safe to assume that only one second changed. - * - * @param[in] _time points to the base time to be added to - * @param[in] _add points to the timestamp to add to the first argument - * - * @return This method returns the number of seconds @a time increased by. - */ -static inline uint32_t _Timestamp64_Add_to_at_tick( - Timestamp64_Control *_time, - const Timestamp64_Control *_add -) -{ - Timestamp64_Control _start = *_time / 1000000000L; - *_time += *_add; - if ( ((*_time) / 1000000000L) != _start ) { - return 1; - } - return 0; -} - /** * @brief Convert Timestamp to Number of Ticks * diff --git a/cpukit/score/include/rtems/score/tod.h b/cpukit/score/include/rtems/score/tod.h index 06cc9003dd..cfb0fe776d 100644 --- a/cpukit/score/include/rtems/score/tod.h +++ b/cpukit/score/include/rtems/score/tod.h @@ -136,6 +136,15 @@ typedef struct { */ Timestamp_Control uptime; + /** + * @brief Time of day seconds trigger. + * + * This value specifies the nanoseconds since the last time of day second. + * It is updated and evaluated in _TOD_Tickle_ticks(). It is set in + * _TOD_Set_with_timestamp(). + */ + uint32_t seconds_trigger; + /** * @brief Indicates if the time of day is set. * diff --git a/cpukit/score/src/coretodset.c b/cpukit/score/src/coretodset.c index 9708ef9477..8b0928af60 100644 --- a/cpukit/score/src/coretodset.c +++ b/cpukit/score/src/coretodset.c @@ -25,6 +25,7 @@ void _TOD_Set_with_timestamp( const Timestamp_Control *tod ) { + uint32_t nanoseconds = _Timestamp_Get_nanoseconds( tod ); Watchdog_Interval seconds_next = _Timestamp_Get_seconds( tod ); Watchdog_Interval seconds_now; @@ -39,6 +40,7 @@ void _TOD_Set_with_timestamp( _Watchdog_Adjust_seconds( WATCHDOG_FORWARD, seconds_next - seconds_now ); _TOD.now = *tod; + _TOD.seconds_trigger = nanoseconds; _TOD.is_set = true; _TOD_Activate(); diff --git a/cpukit/score/src/coretodtickle.c b/cpukit/score/src/coretodtickle.c index fbf67fda79..d0412f85d4 100644 --- a/cpukit/score/src/coretodtickle.c +++ b/cpukit/score/src/coretodtickle.c @@ -35,23 +35,27 @@ void _TOD_Tickle_ticks( void ) { Timestamp_Control tick; - uint32_t seconds; + uint32_t nanoseconds_per_tick; + + nanoseconds_per_tick = rtems_configuration_get_nanoseconds_per_tick(); /* Convert the tick quantum to a timestamp */ - _Timestamp_Set( &tick, 0, rtems_configuration_get_nanoseconds_per_tick() ); + _Timestamp_Set( &tick, 0, nanoseconds_per_tick ); /* Update the counter of ticks since boot */ _Watchdog_Ticks_since_boot += 1; - /* Update the timespec format uptime */ + /* Update the uptime */ _Timestamp_Add_to( &_TOD.uptime, &tick ); /* we do not care how much the uptime changed */ - /* Update the timespec format TOD */ - seconds = _Timestamp_Add_to_at_tick( &_TOD.now, &tick ); - while ( seconds ) { + /* Update the current TOD */ + _Timestamp_Add_to( &_TOD.now, &tick ); + + _TOD.seconds_trigger += nanoseconds_per_tick; + if ( _TOD.seconds_trigger >= 1000000000UL ) { + _TOD.seconds_trigger -= 1000000000UL; _Watchdog_Tickle_seconds(); - seconds--; } } -- cgit v1.2.3