bitbake-user-manual-execution.xml: Update parallelization note.

Update the note to explain that current versions of BitBake automatically calculate the proper values for BB_NUMBER_THREADS

and
PARALLEL_MAKE so you no longer need to set those values manually.

Signed-off-by Robert P. J. Day <[email protected]>

---

doc/bitbake-user-manual/bitbake-user-manual-execution.xml +17 -5

index 8514f23..6d49fb6 100644
@@ -29,11 +29,23 @@
     </para>
 
     <note>
-        Prior to executing BitBake, you should take advantage of parallel
-        thread execution by setting the
-        <link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
-        variable in your <filename>local.conf</filename>
-        configuration file.
+        In order to take advantage of parallel thread execution on your build
+        host, earlier versions of BitBake recommended setting the following
+        variables in your project's <filename>local.conf</filename> file,
+        based on your host's number of CPUs or multithreading
+        capability:
+        <literallayout class='monospaced'>
+     BB_NUMBER_THREADS ?= ...
+     PARALLEL_MAKE ?= ...
+        </literallayout>
+        The current version of BitBake now handles this automatically by
+        assigning default values to those variables as follows:
+        <literallayout class='monospaced'>
+     BB_NUMBER_THREADS ?= "${@oe.utils.cpu_count()}"
+     PARALLEL_MAKE ?= "-j ${@oe.utils.cpu_count()}"
+        </literallayout>
+        so you no longer need to worry about this, unless you specifically
+        want to override this for some reason.
     </note>
 
     <section id='parsing-the-base-configuration-metadata'>

Signature · 9 lines

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

Quoted 2 lines · Robert P. J. Day

Update the note to explain that current versions of BitBake automatically calculate the proper values for BB_NUMBER_THREADS

The current version of bitbake doesn't though.

There is an *OE* helper function which the default local.conf files use.