CVSROOT: /cvs
Module name: src
Changes by: chel...@cvs.openbsd.org 2023/08/10 19:28:19
Modified files:
sys/arch/arm64/dev: agtimer.c
Log message:
agtimer(4/arm64): call CPU_BUSY_CYCLE() during spin-loop
For consistency with other delay(9) implementations, agtimer(4/arm64)
ought to call CPU_BUSY_CYCLE() as it spins.
kettenis@ notes that we could reduce the power consumed in
agtimer_delay() by enabling CNTKCTL_EL1.EVNTEN and configuring
ENTKCTL_EL1.EVNTI.
kettenis@ also notes that Armv8.7 adds FEAT_WFxT, which will, when the
feature appears in real hardware, make it even easier to save power in
agtimer_delay().
With input from drahn@ and kettenis@.
Thread: https://marc.info/?l=openbsd-tech&m=169146193022516&w=2
ok kettenis@
