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| author | Cassio Neri <cassio.neri@gmail.com> | 2021-06-24 23:13:43 +0300 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2021-08-10 01:09:21 +0300 |
| commit | 1d1bb12a8b1805ddeef9793ebeb920179fb0fa38 (patch) | |
| tree | 883add72e000a924a060c2a0a07283ae1ee6f120 /drivers/rtc/Makefile | |
| parent | fffd603ae9f6ee1da47fa4ae4c70c324323bc201 (diff) | |
| download | linux-1d1bb12a8b1805ddeef9793ebeb920179fb0fa38.tar.xz | |
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/Makefile')
| -rw-r--r-- | drivers/rtc/Makefile | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 2dd0dd956b0e..763d3628c603 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -178,3 +178,4 @@ obj-$(CONFIG_RTC_DRV_WM8350) += rtc-wm8350.o obj-$(CONFIG_RTC_DRV_X1205) += rtc-x1205.o obj-$(CONFIG_RTC_DRV_XGENE) += rtc-xgene.o obj-$(CONFIG_RTC_DRV_ZYNQMP) += rtc-zynqmp.o +obj-$(CONFIG_RTC_LIB_KUNIT_TEST) += lib_test.o |