@@ -530,6 +530,33 @@ system and gives an overview of their function and contents.
":ref:`dev-manual/common-tasks:speeding up a build`"
section in the Yocto Project Development Tasks Manual.
+ On the other hand, if your goal is to limit the amount of system
+ resources consumed by BitBake tasks, setting :term:`BB_NUMBER_THREADS`
+ to a number lower than the number of CPU threads in your machine
+ won't be sufficient. That's because each package will still be built
+ and installed through a number of parallel jobs specified by the
+ :term:`PARALLEL_MAKE` variable, which is by default the number of CPU
+ threads in your system, and is not impacted by the
+ :term:`BB_NUMBER_THREADS` value.
+
+ So, if you set :term:`BB_NUMBER_THREADS` to "1" but don't set
+ :term:`PARALLEL_MAKE`, most of your system resources will be consumed
+ anyway.
+
+ Therefore, if you intend to reduce the load of your build system by
+ setting :term:`BB_NUMBER_THREADS` to a relatively low value compared
+ to the number of CPU threads on your system, you should also set
+ :term:`PARALLEL_MAKE` to a similarly low value.
+
+ An alternative to using :term:`BB_NUMBER_THREADS` to keep the usage
+ of build system resources under control is to use the smarter
+ :term:`BB_PRESSURE_MAX_CPU`, :term:`BB_PRESSURE_MAX_IO` or
+ :term:`BB_PRESSURE_MAX_MEMORY` controls. They will prevent BitBake
+ from starting new tasks as long as thresholds are exceeded. Anyway,
+ as with :term:`BB_NUMBER_THREADS`, such controls won't prevent the
+ tasks already being run from using all CPU threads on the system
+ if :term:`PARALLEL_MAKE` is not set to a low value.
+
:term:`BB_SERVER_TIMEOUT`
Specifies the time (in seconds) after which to unload the BitBake
server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how