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Use sleep-aware monotonic clock if available #1189

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Use sleep-aware monotonic clock if available #1189

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bb9ac7b
Use sleep-aware monotonic clock if available
Feb 18, 2025
2e4fef6
Make boot time check a simple define check just like monotonic raw, w…
Mar 10, 2025
733cae5
Merge branch 'main' into BootClock
bretambrose Mar 10, 2025
0a1e0f1
Merge branch 'main' into BootClock
bretambrose Mar 12, 2025
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4 changes: 3 additions & 1 deletion source/posix/clock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,9 @@

static const uint64_t NS_PER_SEC = 1000000000;

#if defined(CLOCK_MONOTONIC_RAW)
#if defined(CLOCK_BOOTTIME)
# define HIGH_RES_CLOCK CLOCK_BOOTTIME
#elif defined(CLOCK_MONOTONIC_RAW)
# define HIGH_RES_CLOCK CLOCK_MONOTONIC_RAW
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Previously we preferred CLOCK_MONOTONIC_RAW:
docs say:

Similar to CLOCK_MONOTONIC, but provides access to a raw hardware-based time that is not subject to NTP adjustments or the incremental adjustments performed by adjtime.

but with this change we'd prefer CLOCK_BOOTTIME, which days say:

Identical to CLOCK_MONOTONIC, except it also includes any time that the system is suspended.

So we'd be subject again to "NTP adjustments or the incremental adjustments performed by adjtime"

Just pointing it out. I don't know enough about this off the top of my head to gauge the full repercussions

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OK. I just did some more reading on all this. BOOTTIME seems fine for our purposes.

#else
# define HIGH_RES_CLOCK CLOCK_MONOTONIC
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