mirrors/poky
1
0
Fork 0
mirror of https://git.yoctoproject.org/poky synced 2026-04-04 23:02:22 +02:00
Code Issues Packages Projects Releases Wiki Activity

ref-manual/variables.rst: expand BB_NUMBER_THREADS description

Browse Source 
Explain that reducing its value to reduce system load
is not sufficient if PARALLEL_MAKE is not reduced as well.

(From yocto-docs rev: f4986faa5576ec1c146e606220421a686c4a9b57)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Michael Opdenacker
2022-11-08 19:36:16 +01:00
committed by Richard Purdie
parent e39e68053f
commit 15a8edcead
1 changed files with 27 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
documentation/ref-manual/variables.rst
View File

@@ -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