Changeset 5ce1bdb

Timestamp:

06/30/2020 05:45:38 PM (4 years ago)

Author:

Ken Moffat <ken@…>

Branches:

10.0, 10.1, 11.0, 11.1, 11.2, 11.3, 12.0, 12.1, kea, ken/TL2024, ken/inkscape-core-mods, ken/tuningfonts, lazarus, lxqt, plabs/newcss, plabs/python-mods, python3.11, qt5new, rahul/power-profiles-daemon, renodr/vulkan-addition, trunk, upgradedb, xry111/intltool, xry111/llvm18, xry111/soup3, xry111/test-20220226, xry111/xf86-video-removal

Children:

eb7de89

Parents:

693f28e1

Message:

Rust: explain how to (mostly) restrict how many processors it wants to use.

git-svn-id: svn://svn.linuxfromscratch.org/BLFS/trunk/BOOK@23349 af4574ff-66df-0310-9fd7-8a98e5e911e0

Files:

• general/prog/rust.xml (modified) (1 diff)
• introduction/important/building-notes.xml (modified) (1 diff)
• introduction/welcome/changelog.xml (modified) (1 diff)

general/prog/rust.xml

@@ -102 +102 @@
       all available processors, although it does not scale well and often falls
       back to just using one core while waiting for a library to compile.
+      However it can be mostly limited to a specified number of processors by
+      a combination of adding the switch <literal>--jobs &lt;N&gt;</literal>
+      (e.g. '--jobs 4' to limit to 4 processors) on each invocation of
+      <command>python3 ./x.py</command> <emphasis>and</emphasis> using an
+      environment variable <envar>CARGO_BUILD_JOBS=&lt;N&gt;</envar>. At the
+      moment this is not effective when some of the rustc tests are run.
     </para>
 

introduction/important/building-notes.xml

@@ -666 +666 @@
       </para>
 
+      <para>
+        The rust developers seem to assume that everyone will compile on a
+        machine dedicated to producing builds, so by default all CPUs are used.
+        This can often be worked around, either by exporting
+        CARGO_BUILD_JOBS=&lt;N&gt; or passing --jobs &lt;N&gt; to cargo. For
+        compiling rustc itself, specifying --jobs &lt;N&gt; on invocations of
+        x.py (together with the <envar>CARGO_BUILD_JOBS</envar> environment
+        variable, which looks like a "belt and braces" approach but seems to be
+        necessary) mostly works. The exception is running the tests when building
+        rustc, some of them will nevertheless use all online CPUs, at least as of
+        rustc-1.42.0.
+      </para>
+
   </sect2>
 

introduction/welcome/changelog.xml

@@ -46 +46 @@
       <itemizedlist>
         <listitem>
+          <para>[ken] - note that building rustc can now mostly be restricted to
+          a specified number of processors by adding a --jobs switch to each x.py
+          command and also exporting CARGO_BUILD_JOBS= with a value.</para>
+        </listitem>
+        <listitem>
           <para>[ken] - Pierre discovered that building firefox-78 requires
           that Python3 has been rebuilt after installing sqlite3.</para>