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2760105516
The current implementation of time64_to_tm() contains unnecessary loops, branches and look-up tables. The new one uses an arithmetic-based algorithm appeared in [1] and is approximately 3x faster (YMMV). The drawback is that the new code isn't intuitive and contains many 'magic numbers' (not unusual for this type of algorithm). However, [1] justifies all those numbers and, given this function's history, the code is unlikely to need much maintenance, if any at all. Add a KUnit test for it which checks every day in a 160,000 years interval centered at 1970-01-01 against the expected result. [1] Neri, Schneider, "Euclidean Affine Functions and Applications to Calendar Algorithms". https://arxiv.org/abs/2102.06959 Signed-off-by: Cassio Neri <cassio.neri@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210622213616.313046-1-cassio.neri@gmail.com
25 lines
986 B
Makefile
25 lines
986 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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obj-y += time.o timer.o hrtimer.o
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obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
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obj-y += timeconv.o timecounter.o alarmtimer.o
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ifeq ($(CONFIG_POSIX_TIMERS),y)
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obj-y += posix-timers.o posix-cpu-timers.o posix-clock.o itimer.o
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else
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obj-y += posix-stubs.o
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endif
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obj-$(CONFIG_GENERIC_CLOCKEVENTS) += clockevents.o tick-common.o
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ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y)
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obj-y += tick-broadcast.o
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obj-$(CONFIG_TICK_ONESHOT) += tick-broadcast-hrtimer.o
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endif
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obj-$(CONFIG_GENERIC_SCHED_CLOCK) += sched_clock.o
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obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o tick-sched.o
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obj-$(CONFIG_LEGACY_TIMER_TICK) += tick-legacy.o
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obj-$(CONFIG_HAVE_GENERIC_VDSO) += vsyscall.o
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obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o
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obj-$(CONFIG_TEST_UDELAY) += test_udelay.o
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obj-$(CONFIG_TIME_NS) += namespace.o
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obj-$(CONFIG_TEST_CLOCKSOURCE_WATCHDOG) += clocksource-wdtest.o
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obj-$(CONFIG_TIME_KUNIT_TEST) += time_test.o
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