Add a separate section for low-resolution generic counter for ARM64 profiling methods.
Signed-off-by: Dharmik Thakkar <dharmik.thak...@arm.com> Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> Reviewed-by: Phil Yang <phil.y...@arm.com> --- doc/guides/prog_guide/profile_app.rst | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/doc/guides/prog_guide/profile_app.rst b/doc/guides/prog_guide/profile_app.rst index a36ebef4db99..e5d0e9079e11 100644 --- a/doc/guides/prog_guide/profile_app.rst +++ b/doc/guides/prog_guide/profile_app.rst @@ -57,11 +57,16 @@ For more derails refer to the `ARM64 specific PMU events enumeration <http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100095_0002_04_en/way1382543438508.html>`_. -High-resolution cycle counter -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Low-resolution generic counter +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The default ``cntvct_el0`` based ``rte_rdtsc()`` provides a portable means to -get a wall clock counter in user space. Typically it runs at <= 100MHz. +get a wall clock counter in user space. Typically it runs at a lower clock frequency than the CPU clock frequency. +Cycles counted using this method should be scaled to CPU clock frequency. + + +High-resolution cycle counter +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The alternative method to enable ``rte_rdtsc()`` for a high resolution wall clock counter is through the ARMv8 PMU subsystem. The PMU cycle counter runs -- 2.20.1
