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authorCassio Neri <cassio.neri@gmail.com>2021-06-24 21:13:43 +0100
committerAlexandre Belloni <alexandre.belloni@bootlin.com>2021-08-10 00:09:21 +0200
commit1d1bb12a8b1805ddeef9793ebeb920179fb0fa38 (patch)
tree883add72e000a924a060c2a0a07283ae1ee6f120 /drivers/rtc/Kconfig
parentfffd603ae9f6ee1da47fa4ae4c70c324323bc201 (diff)
rtc: Improve performance of rtc_time64_to_tm(). Add tests.
The current implementation of rtc_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 4.3 times 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 case that checks every day in a 160,000 years interval starting on 1970-01-01 against the expected result. Add a new config RTC_LIB_KUNIT_TEST symbol to give the option to run this test suite. [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> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20210624201343.85441-1-cassio.neri@gmail.com
Diffstat (limited to 'drivers/rtc/Kconfig')
-rw-r--r--drivers/rtc/Kconfig10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 12153d5801ce..b3cf3a274c05 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -10,6 +10,16 @@ config RTC_MC146818_LIB
bool
select RTC_LIB
+config RTC_LIB_KUNIT_TEST
+ tristate "KUnit test for RTC lib functions" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ select RTC_LIB
+ help
+ Enable this option to test RTC library functions.
+
+ If unsure, say N.
+
menuconfig RTC_CLASS
bool "Real Time Clock"
default n