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/src/coretodtickle.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) (limited to 'cpukit/score/src/coretodtickle.c') 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