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diff --git a/doc/manual/advanced-topics/cores-vs-jobs.xml b/doc/manual/advanced-topics/cores-vs-jobs.xml deleted file mode 100644 index 4d58ac7c5..000000000 --- a/doc/manual/advanced-topics/cores-vs-jobs.xml +++ /dev/null @@ -1,121 +0,0 @@ -<chapter xmlns="http://docbook.org/ns/docbook" - xmlns:xlink="http://www.w3.org/1999/xlink" - xmlns:xi="http://www.w3.org/2001/XInclude" - version="5.0" - xml:id="chap-tuning-cores-and-jobs"> - -<title>Tuning Cores and Jobs</title> - -<para>Nix has two relevant settings with regards to how your CPU cores -will be utilized: <xref linkend="conf-cores" /> and -<xref linkend="conf-max-jobs" />. This chapter will talk about what -they are, how they interact, and their configuration trade-offs.</para> - -<variablelist> - <varlistentry> - <term><xref linkend="conf-max-jobs" /></term> - <listitem><para> - Dictates how many separate derivations will be built at the same - time. If you set this to zero, the local machine will do no - builds. Nix will still substitute from binary caches, and build - remotely if remote builders are configured. - </para></listitem> - </varlistentry> - <varlistentry> - <term><xref linkend="conf-cores" /></term> - <listitem><para> - Suggests how many cores each derivation should use. Similar to - <command>make -j</command>. - </para></listitem> - </varlistentry> -</variablelist> - -<para>The <xref linkend="conf-cores" /> setting determines the value of -<envar>NIX_BUILD_CORES</envar>. <envar>NIX_BUILD_CORES</envar> is equal -to <xref linkend="conf-cores" />, unless <xref linkend="conf-cores" /> -equals <literal>0</literal>, in which case <envar>NIX_BUILD_CORES</envar> -will be the total number of cores in the system.</para> - -<para>The maximum number of consumed cores is a simple multiplication, -<xref linkend="conf-max-jobs" /> * <envar>NIX_BUILD_CORES</envar>.</para> - -<para>The balance on how to set these two independent variables depends -upon each builder's workload and hardware. Here are a few example -scenarios on a machine with 24 cores:</para> - -<table> - <caption>Balancing 24 Build Cores</caption> - <thead> - <tr> - <th><xref linkend="conf-max-jobs" /></th> - <th><xref linkend="conf-cores" /></th> - <th><envar>NIX_BUILD_CORES</envar></th> - <th>Maximum Processes</th> - <th>Result</th> - </tr> - </thead> - <tbody> - <tr> - <td>1</td> - <td>24</td> - <td>24</td> - <td>24</td> - <td> - One derivation will be built at a time, each one can use 24 - cores. Undersold if a job can’t use 24 cores. - </td> - </tr> - - <tr> - <td>4</td> - <td>6</td> - <td>6</td> - <td>24</td> - <td> - Four derivations will be built at once, each given access to - six cores. - </td> - </tr> - <tr> - <td>12</td> - <td>6</td> - <td>6</td> - <td>72</td> - <td> - 12 derivations will be built at once, each given access to six - cores. This configuration is over-sold. If all 12 derivations - being built simultaneously try to use all six cores, the - machine's performance will be degraded due to extensive context - switching between the 12 builds. - </td> - </tr> - <tr> - <td>24</td> - <td>1</td> - <td>1</td> - <td>24</td> - <td> - 24 derivations can build at the same time, each using a single - core. Never oversold, but derivations which require many cores - will be very slow to compile. - </td> - </tr> - <tr> - <td>24</td> - <td>0</td> - <td>24</td> - <td>576</td> - <td> - 24 derivations can build at the same time, each using all the - available cores of the machine. Very likely to be oversold, - and very likely to suffer context switches. - </td> - </tr> - </tbody> -</table> - -<para>It is up to the derivations' build script to respect -host's requested cores-per-build by following the value of the -<envar>NIX_BUILD_CORES</envar> environment variable.</para> - -</chapter> |