kernel: Improve precision of ticks and ms conversions #9745
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cvinayak
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Aug 31, 2018
include/kernel.h
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| @@ -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); | |||
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I think I had an extra space prefixed here.
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Codecov Report
@@ Coverage Diff @@
## master #9745 +/- ##
=======================================
Coverage 52.24% 52.24%
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Files 212 212
Lines 25950 25950
Branches 5593 5593
=======================================
Hits 13557 13557
Misses 10159 10159
Partials 2234 2234
Continue to review full report at Codecov.
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@nashif not sure about the failures, seem related to stack overflow |
The following 2 improvements are contained in this patch: - When converting from ms to ticks, instead of using hardware cycles per tick, use hardware cycles per second. This ensures that the multiplication is done before the division, increasing precision. - When converting from ticks to ms, instead of using cycles per tick and cycles per sec, use ticks per sec. This too increases the precision. The concept is to make the dividend as large as possible compared to the divisor in order to lose as little precision as possible. Fixes zephyrproject-rtos#8898 Fixes zephyrproject-rtos#9459 Fixes zephyrproject-rtos#9466 Fixes zephyrproject-rtos#9468 Signed-off-by: Vinayak Kariappa Chettimada <[email protected]> Signed-off-by: Carles Cufi <[email protected]>
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Failed with:
Running test suite suite_preempt
===================================================================
starting test - test_preempt
***** Stack Check Fail! *****
Current thread ID = 0x0040019c
eax: 0x00400254, ebx: 0x00400254, ecx: 0x004002b0, edx: 0x00000001
esi: 0x004001f8, edi: 0x00401080, ebp: 0x00408024, esp: 0x00408000
eflags: 0x00000046 cs: 0x0008
call trace:
eip: 0x00002115
0x000021b8 (0x40019c)
0x00002685 (0x4001f8)
0x00004f65 (0x401120)
0x00005187 (0x401120)
0x000051c2 (0x40019c)
0x000052be (0xffffffff)
0x00005bab (0x246)
0x000019c4 (0x400078)
Fatal fault in thread 0x0040019c! Aborting.
Signed-off-by: Anas Nashif <[email protected]>
carlescufi
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pswarnak and
spoorthik
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nashif
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Aug 31, 2018
This was referenced Sep 11, 2018
This was referenced Jan 15, 2019
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The following 2 improvements are contained in this patch:
per tick, use hardware cycles per second. This ensures that the
multiplication is done before the division, increasing precision.
and cycles per sec, use ticks per sec. This too increases the
precision.
The concept is to make the dividend as large as possible compared to the
divisor in order to lose as little precision as possible.
Fixes #8898
Fixes #9459
Fixes #9466
Fixes #9468
Signed-off-by: Vinayak Kariappa Chettimada [email protected]