path: root/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
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authorScott Rifenbark <srifenbark@gmail.com>2018-06-18 15:06:16 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2018-06-19 17:08:51 +0100
commit4937ed392fdc4442dd91f644f329dda29f27242c (patch)
treee750e87f591a2d924042e9b4bb89a00a2d8654c4 /doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
parent055865047c63b9c3b213b47a1884924ce0adeda0 (diff)
bitbake-user-manual: Added "number_threads" varflag
You can now limit on a task-specific basis the number of threads a task will use. This is useful for machines that have high numbers of cores and need to be rate-limited due to various resource constraints. Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'doc/bitbake-user-manual/bitbake-user-manual-metadata.xml')
1 files changed, 32 insertions, 0 deletions
diff --git a/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml b/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
index b4fc64e7..bc08c814 100644
--- a/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
+++ b/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
@@ -1929,6 +1929,38 @@
not careful.
+ <listitem><para><emphasis><filename>[number_threads]</filename>:</emphasis>
+ Limits tasks to a specific number of simultaneous threads
+ during execution.
+ This varflag is useful when your build host has a large number
+ of cores but certain tasks need to be rate-limited due to various
+ kinds of resource constraints (e.g. to avoid network throttling).
+ <filename>number_threads</filename> works similarly to the
+ <link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
+ variable but is task-specific.</para>
+ <para>Set the value globally.
+ For example, the following makes sure the
+ <filename>do_fetch</filename> task uses no more than two
+ simultaneous execution threads:
+ <literallayout class='monospaced'>
+ do_fetch[number_threads] = "2"
+ </literallayout>
+ <note><title>Warnings</title>
+ <itemizedlist>
+ <listitem><para>
+ Setting the varflag in individual recipes rather
+ than globally can result in unpredictable behavior.
+ </para></listitem>
+ <listitem><para>
+ Setting the varflag to a value greater than the
+ value used in the <filename>BB_NUMBER_THREADS</filename>
+ variable causes <filename>number_threads</filename>
+ to have no effect.
+ </para></listitem>
+ </itemizedlist>
+ </note>
+ </para></listitem>
List of functions to call after the completion of the task.