From e9eb92e88881215a3f3a86fec9a895e9a95f7168 Mon Sep 17 00:00:00 2001 From: Elaine Fonaro Date: Fri, 10 Jun 2022 16:29:28 -0300 Subject: [PATCH] Disable nohz_full in standard kernels Updated the procedure ~(keystone)admin)$ system host-unlock and updated information about Standard Systems. Minor updates (rewrited a sentence and corrected spelling error. Created a sub-section to add the Disable nohz_full label step-by-step. Signed-off-by: Elaine Fonaro Change-Id: I7999a17cd21d3ed73ef58a25ffd727ce245e7233 --- ...res-to-enhance-application-performance.rst | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/doc/source/admintasks/kubernetes/isolating-cpu-cores-to-enhance-application-performance.rst b/doc/source/admintasks/kubernetes/isolating-cpu-cores-to-enhance-application-performance.rst index 4b5113201..193f805df 100644 --- a/doc/source/admintasks/kubernetes/isolating-cpu-cores-to-enhance-application-performance.rst +++ b/doc/source/admintasks/kubernetes/isolating-cpu-cores-to-enhance-application-performance.rst @@ -76,3 +76,45 @@ running :command:`sched_getaffinity()` command, or by parsing Isolated CPUs can be identified in the container by looking for files such as ``/dev/cpu/`` where ```` is a number, or by referencing ``/sys/devices/system/cpu/isolated`` against the CPUs associated with this container. + + +------------------------------------- +Isolating CPU Cores from Kernel Noise +------------------------------------- + +For better performance of latency-sensitive applications, and to improve energy +efficiency on idle CPUs, it is possible to isolate CPU cores from kernel noise +with the ``nohz_full`` kernel parameter. This configuration is supported in both +low-latency and standard kernel types. However, for standard kernels, it is +possible to disable the CPU isolation by assigning a label to the target host +with worker sub function. + +To summarize, the configuration is supported by default in workers of any +kernel type, but for standard kernels, you can enable the ``disable-nohz-full`` +label to disable it. + +Use the procedure below to disable the ``nohz_full`` parameter on standard +kernels: + +.. rubric:: |proc| + +#. Lock the host. + + .. code-block:: none + + ~(keystone)admin)$ system host-lock + +#. Assign the ``disable-nohz-full`` label. + + .. code-block:: none + + ~(keystone)admin)$ system host-label-assign disable-nohz-full=enabled + +#. Unlock the host. + + .. code-block:: none + + ~(keystone)admin)$ system host-unlock + +.. note:: + ``disable-nohz-full`` label can be also assigned via the GUI. \ No newline at end of file