* [PATCH RESEND v3] doc: bitbake-user-manual: Add definition for BB_PRESSURE_MAX variables
[not found] <17111BB47189E793.5304@lists.yoctoproject.org>
@ 2022-09-19 14:58 ` michael.opdenacker
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From: michael.opdenacker @ 2022-09-19 14:58 UTC (permalink / raw)
To: bitbake-devel
Cc: docs, Michael Opdenacker, Aryaman Gupta, Randy Macleod,
Quentin Schulz
From: Michael Opdenacker <michael.opdenacker@bootlin.com>
From: Aryaman Gupta <aryaman.gupta@windriver.com>
Add the definitions for the BB_PRESSURE_MAX{CPU|IO|MEMORY} variables in the
bitbake varibales glossary. Further information on how to determine a good
threshold will be added to the Yocto reference manual in a later commit.
Signed-off-by: Aryaman Gupta <aryaman.gupta@windriver.com>
Signed-off-by: Randy Macleod <Randy.Macleod@windriver.com>
Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Quentin Schulz <foss+yocto@0leil.net>
---
Changes in V3 (Michael Opdenacker):
- Remove reference to Yocto Project manual, not documenting
the variables yet.
- Fix a typo ("it's" -> "its")
- Simplify syntax (":" followed by "::" replaced by "::"
---
.../bitbake-user-manual-ref-variables.rst | 25 +++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
index 12aef3cb..725e6c2c 100644
--- a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
+++ b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
@@ -483,6 +483,31 @@ overview of their function and contents.
You must set this variable in the external environment in order
for it to work.
+ :term:`BB_PRESSURE_MAX_CPU`
+ The threshold for maximum CPU pressure before BitBake prevents the
+ scheduling of new tasks. Once the :term:`BB_PRESSURE_MAX_CPU` threshold
+ is exceeded, new tasks are not started until the pressure subsides to
+ below the threshold. If :term:`BB_PRESSURE_MAX_CPU` is not set, CPU
+ pressure is not monitored. A threshold can be set in ``conf/local.conf``
+ as::
+
+ BB_PRESSURE_MAX_CPU = "500"
+
+ :term:`BB_PRESSURE_MAX_IO`
+ The threshold for maximum IO pressure experienced before BitBake
+ prevents the scheduling of new tasks. The IO pressure is regulated in the
+ same way as :term:`BB_PRESSURE_MAX_CPU`. At this point in time,
+ experiments show that IO pressure tends to be short-lived and regulating
+ just the CPU can help to reduce it.
+
+ :term:`BB_PRESSURE_MAX_MEMORY`
+ The threshold for maximum memory pressure experienced before BitBake
+ prevents the scheduling of new tasks. The memory pressure is regulated in
+ the same way as :term:`BB_PRESSURE_MAX_CPU`. Note that any memory
+ pressure indicates that a system is being pushed beyond its capacity. At
+ this point in time, experiments show that memory pressure tends to be
+ short-lived and regulating just the CPU can help to reduce it.
+
:term:`BB_RUNFMT`
Specifies the name of the executable script files (i.e. run files)
saved into ``${``\ :term:`T`\ ``}``. By default, the
--
2.34.1
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