[project @ 2005-05-16 14:40:06 by simonmar]

document +RTS -I

diff --git a/ghc/docs/users_guide/runtime_control.xml b/ghc/docs/users_guide/runtime_control.xml
index 837d99f..e779ce3 100644 (file)
--- a/ghc/docs/users_guide/runtime_control.xml
+++ b/ghc/docs/users_guide/runtime_control.xml
@@ -245,6 +245,39 @@
 
       <varlistentry>
        <term>
+         <option>-I</option><replaceable>seconds</replaceable>
+         <indexterm><primary><option>-H</option></primary>
+           <secondary>RTS option</secondary>
+         </indexterm>
+         <indexterm><primary>idle GC</primary>
+         </indexterm>
+         </term>
+       <listitem>
+         <para>(default: 0.3) In the threaded and SMP versions of the RTS (see
+           <option>-threaded</option>, <xref linkend="options-linker" />), a
+           major GC is automatically performed if the runtime has been idle
+           (no Haskell computation has been running) for a period of time.
+           The amount of idle time which must pass before a GC is performed is
+           set by the <option>-I</option><replaceable>seconds</replaceable>
+           option.  Specifying <option>-I0</option> disables the idle GC.</para>
+
+         <para>For an interactive application, it is probably a good idea to
+           use the idle GC, because this will allow finalizers to run and
+           deadlocked threads to be detected in the idle time when no Haskell
+           computation is happening.  Also, it will mean that a GC is less
+           likely to happen when the application is busy, and so
+           responsiveness may be improved.   However, if the amount of live data in
+           the heap is particularly large, then the idle GC can cause a
+           significant delay, and too small an interval could adversely affect
+           interactive responsiveness.</para>
+
+         <para>This is an experimental feature, please let us know if it
+           causes problems and/or could benefit from further tuning.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>
          <option>-k</option><replaceable>size</replaceable>
          <indexterm><primary><option>-k</option></primary><secondary>RTS option</secondary></indexterm>
          <indexterm><primary>stack, minimum size</primary></indexterm>