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kernel: Improve precision of ticks and ms conversions #9745

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Merged
merged 2 commits into from
Aug 31, 2018
Merged

kernel: Improve precision of ticks and ms conversions #9745

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bc087b3
kernel: Improve precision of ticks and ms conversions
cvinayak Aug 31, 2018
fbba8ec
tests: preempt: increase stack size for test
nashif Aug 31, 2018
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6 changes: 3 additions & 3 deletions include/kernel.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1363,7 +1363,8 @@ static ALWAYS_INLINE s32_t _ms_to_ticks(s32_t ms)
/* use 64-bit math to keep precision */
return (s32_t)ceiling_fraction(
(s64_t)ms * sys_clock_hw_cycles_per_sec,
(s64_t)MSEC_PER_SEC * sys_clock_hw_cycles_per_tick);
((s64_t)MSEC_PER_SEC * sys_clock_hw_cycles_per_sec) /
sys_clock_ticks_per_sec);
#else
/* simple division keeps precision */
s32_t ms_per_tick = MSEC_PER_SEC / sys_clock_ticks_per_sec;
Expand All @@ -1383,8 +1384,7 @@ static inline s64_t __ticks_to_ms(s64_t ticks)

#ifdef _NEED_PRECISE_TICK_MS_CONVERSION
/* use 64-bit math to keep precision */
return (u64_t)ticks * sys_clock_hw_cycles_per_tick * MSEC_PER_SEC /
sys_clock_hw_cycles_per_sec;
return (u64_t)ticks * MSEC_PER_SEC / sys_clock_ticks_per_sec;
#else
/* simple multiplication keeps precision */
u32_t ms_per_tick = MSEC_PER_SEC / sys_clock_ticks_per_sec;
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1 change: 1 addition & 0 deletions tests/kernel/sched/preempt/prj.conf
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Expand Up @@ -2,3 +2,4 @@ CONFIG_ZTEST=y
CONFIG_MP_NUM_CPUS=1
CONFIG_NUM_METAIRQ_PRIORITIES=1
CONFIG_IRQ_OFFLOAD=y
CONFIG_TEST_EXTRA_STACKSIZE=256