[dpdk-dev] [PATCH 5/5] doc: add aarch64 generic counter section
Dharmik Thakkar
dharmik.thakkar at arm.com
Wed May 6 23:58:47 CEST 2020
Add a separate section for low-resolution generic counter
for ARM64 profiling methods.
Signed-off-by: Dharmik Thakkar <dharmik.thakkar at arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
Reviewed-by: Phil Yang <phil.yang at 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
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