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Reimplement the arm64 dtrace_gethrtime(), which provides the

Description

Reimplement the arm64 dtrace_gethrtime(), which provides the
high-resolution nanosecond timestamp used for the DTrace 'timestamp'
built-in variable. The new implementation uses the EL0 cycle
counter and frequency registers in ARMv8-A. This replaces a
previous implementation that relied on an instrumentation-safe
implementation of getnanotime(), which provided only timer
resolution.

MFC after: 3 days
Reviewed by: andrew, bsdimp (older version)
Useful comments appreciated: jrtc27, emaste

Details

Provenance
rwatsonAuthored on Feb 16 2021, 3:19 PM
Parents
R10:50b7c1f530f1: ofwfb: fix incorrect colors on powerpc* and add new tunable parameters
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