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authorScott Rifenbark <srifenbark@gmail.com>2018-01-23 11:29:22 -0800
committerRichard Purdie <richard.purdie@linuxfoundation.org>2018-02-14 15:25:29 +0000
commit30b91e6d891fbfa6a44487a27b8ceb5618157614 (patch)
treea55464032253d643fc4ceec7952cc32e656fdc26 /documentation/dev-manual/dev-manual-start.xml
parent355103f8cf2295fb2de91ce25a084e286bdeadeb (diff)
downloadpoky-30b91e6d891fbfa6a44487a27b8ceb5618157614.tar.gz
documentation: Removed "usingpoky" chapter from ref-manual
Fixes [YOCTO #12370] All of the information from the "usingpoky" chapter in the ref-manual has been distributed out over the rest of the YP manual set. Primarily, this information went into the dev-manual and the overview-manual. Because the chapter is no more, I had to update the mega-manual.xml to not include that chapter. Also, had to update ref-manual to exclude the chapter as part of the Make process. (From yocto-docs rev: b988cab06d42f0ac2220cefe66949c5ab6cbf803) Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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diff --git a/documentation/dev-manual/dev-manual-start.xml b/documentation/dev-manual/dev-manual-start.xml
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+++ b/documentation/dev-manual/dev-manual-start.xml
@@ -840,6 +840,171 @@
840 </orderedlist> 840 </orderedlist>
841 </para> 841 </para>
842</section> 842</section>
843
844<section id='speeding-up-the-build'>
845 <title>Speeding Up the Build</title>
846
847 <para>
848 Build time can be an issue.
849 By default, the build system uses simple controls to try and maximize
850 build efficiency.
851 In general, the default settings for all the following variables
852 result in the most efficient build times when dealing with single
853 socket systems (i.e. a single CPU).
854 If you have multiple CPUs, you might try increasing the default
855 values to gain more speed.
856 See the descriptions in the glossary for each variable for more
857 information:
858 <itemizedlist>
859 <listitem><para>
860 <link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename>:</link>
861 The maximum number of threads BitBake simultaneously executes.
862 </para></listitem>
863 <listitem><para>
864 <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_NUMBER_PARSE_THREADS'><filename>BB_NUMBER_PARSE_THREADS</filename>:</ulink>
865 The number of threads BitBake uses during parsing.
866 </para></listitem>
867 <listitem><para>
868 <link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename>:</link>
869 Extra options passed to the <filename>make</filename> command
870 during the
871 <link linkend='ref-tasks-compile'><filename>do_compile</filename></link>
872 task in order to specify parallel compilation on the
873 local build host.
874 </para></listitem>
875 <listitem><para>
876 <link linkend='var-PARALLEL_MAKEINST'><filename>PARALLEL_MAKEINST</filename>:</link>
877 Extra options passed to the <filename>make</filename> command
878 during the
879 <link linkend='ref-tasks-install'><filename>do_install</filename></link>
880 task in order to specify parallel installation on the
881 local build host.
882 </para></listitem>
883 </itemizedlist>
884 As mentioned, these variables all scale to the number of processor
885 cores available on the build system.
886 For single socket systems, this auto-scaling ensures that the build
887 system fundamentally takes advantage of potential parallel operations
888 during the build based on the build machine's capabilities.
889 </para>
890
891 <para>
892 Following are additional factors that can affect build speed:
893 <itemizedlist>
894 <listitem><para>
895 File system type:
896 The file system type that the build is being performed on can
897 also influence performance.
898 Using <filename>ext4</filename> is recommended as compared
899 to <filename>ext2</filename> and <filename>ext3</filename>
900 due to <filename>ext4</filename> improved features
901 such as extents.
902 </para></listitem>
903 <listitem><para>
904 Disabling the updating of access time using
905 <filename>noatime</filename>:
906 The <filename>noatime</filename> mount option prevents the
907 build system from updating file and directory access times.
908 </para></listitem>
909 <listitem><para>
910 Setting a longer commit:
911 Using the "commit=" mount option increases the interval
912 in seconds between disk cache writes.
913 Changing this interval from the five second default to
914 something longer increases the risk of data loss but decreases
915 the need to write to the disk, thus increasing the build
916 performance.
917 </para></listitem>
918 <listitem><para>
919 Choosing the packaging backend:
920 Of the available packaging backends, IPK is the fastest.
921 Additionally, selecting a singular packaging backend also
922 helps.
923 </para></listitem>
924 <listitem><para>
925 Using <filename>tmpfs</filename> for
926 <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>
927 as a temporary file system:
928 While this can help speed up the build, the benefits are
929 limited due to the compiler using
930 <filename>-pipe</filename>.
931 The build system goes to some lengths to avoid
932 <filename>sync()</filename> calls into the
933 file system on the principle that if there was a significant
934 failure, the
935 <link linkend='build-directory'>Build Directory</link>
936 contents could easily be rebuilt.
937 </para></listitem>
938 <listitem><para>
939 Inheriting the
940 <link linkend='ref-classes-rm-work'><filename>rm_work</filename></link>
941 class:
942 Inheriting this class has shown to speed up builds due to
943 significantly lower amounts of data stored in the data
944 cache as well as on disk.
945 Inheriting this class also makes cleanup of
946 <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>
947 faster, at the expense of being easily able to dive into the
948 source code.
949 File system maintainers have recommended that the fastest way
950 to clean up large numbers of files is to reformat partitions
951 rather than delete files due to the linear nature of partitions.
952 This, of course, assumes you structure the disk partitions and
953 file systems in a way that this is practical.
954 </para></listitem>
955 </itemizedlist>
956 Aside from the previous list, you should keep some trade offs in
957 mind that can help you speed up the build:
958 <itemizedlist>
959 <listitem><para>
960 Remove items from
961 <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>
962 that you might not need.
963 </para></listitem>
964 <listitem><para>
965 Exclude debug symbols and other debug information:
966 If you do not need these symbols and other debug information,
967 disabling the <filename>*-dbg</filename> package generation
968 can speed up the build.
969 You can disable this generation by setting the
970 <link linkend='var-INHIBIT_PACKAGE_DEBUG_SPLIT'><filename>INHIBIT_PACKAGE_DEBUG_SPLIT</filename></link>
971 variable to "1".
972 </para></listitem>
973 <listitem><para>
974 Disable static library generation for recipes derived from
975 <filename>autoconf</filename> or <filename>libtool</filename>:
976 Following is an example showing how to disable static
977 libraries and still provide an override to handle exceptions:
978 <literallayout class='monospaced'>
979 STATICLIBCONF = "--disable-static"
980 STATICLIBCONF_sqlite3-native = ""
981 EXTRA_OECONF += "${STATICLIBCONF}"
982 </literallayout>
983 <note><title>Notes</title>
984 <itemizedlist>
985 <listitem><para>
986 Some recipes need static libraries in order to work
987 correctly (e.g. <filename>pseudo-native</filename>
988 needs <filename>sqlite3-native</filename>).
989 Overrides, as in the previous example, account for
990 these kinds of exceptions.
991 </para></listitem>
992 <listitem><para>
993 Some packages have packaging code that assumes the
994 presence of the static libraries.
995 If so, you might need to exclude them as well.
996 </para></listitem>
997 </itemizedlist>
998 </note>
999 </para></listitem>
1000 </itemizedlist>
1001 </para>
1002</section>
1003
1004
1005
1006
1007
843</chapter> 1008</chapter>
844<!-- 1009<!--
845vim: expandtab tw=80 ts=4 1010vim: expandtab tw=80 ts=4