Repository : ssh://darcs.haskell.org//srv/darcs/ghc On branch : master
http://hackage.haskell.org/trac/ghc/changeset/f65bbbe02555b20e219e4ad3a540d385ae393092 >--------------------------------------------------------------- commit f65bbbe02555b20e219e4ad3a540d385ae393092 Author: Simon Marlow <[email protected]> Date: Fri Oct 7 14:47:51 2011 +0100 document the -H option >--------------------------------------------------------------- docs/users_guide/runtime_control.xml | 38 ++++++++++++++++++++------------- 1 files changed, 23 insertions(+), 15 deletions(-) diff --git a/docs/users_guide/runtime_control.xml b/docs/users_guide/runtime_control.xml index 48ea0a8..2af87bc 100644 --- a/docs/users_guide/runtime_control.xml +++ b/docs/users_guide/runtime_control.xml @@ -543,26 +543,34 @@ char *ghc_rts_opts = "-H128m -K1m"; <varlistentry> <term> - <option>-H</option><replaceable>size</replaceable> + <option>-H</option><optional><replaceable>size</replaceable></optional> <indexterm><primary><option>-H</option></primary><secondary>RTS option</secondary></indexterm> <indexterm><primary>heap size, suggested</primary></indexterm> </term> <listitem> <para>[Default: 0] This option provides a - “suggested heap size” for the garbage collector. The - garbage collector will use about this much memory until the - program residency grows and the heap size needs to be - expanded to retain reasonable performance.</para> - - <para>By default, the heap will start small, and grow and - shrink as necessary. This can be bad for performance, so if - you have plenty of memory it's worthwhile supplying a big - <option>-H</option><replaceable>size</replaceable>. For - improving GC performance, using - <option>-H</option><replaceable>size</replaceable> is - usually a better bet than - <option>-A</option><replaceable>size</replaceable>.</para> - </listitem> + “suggested heap size” for the garbage + collector. Think + of <option>-H<replaceable>size</replaceable></option> as a + variable <option>-A</option> option. It says: I want to + use at least <replaceable>size</replaceable> bytes, so use + whatever is left over to increase the <option>-A</option> + value.</para> + + <para>This option does not put + a <emphasis>limit</emphasis> on the heap size: the heap + may grow beyond the given size as usual.</para> + + <para>If <replaceable>size</replaceable> is omitted, then + the garbage collector will take the size of the heap at + the previous GC as the <replaceable>size</replaceable>. + This has the effect of allowing for a + larger <option>-A</option> value but without increasing + the overall memory requirements of the program. It can be + useful when the default small <option>-A</option> value is + suboptimal, as it can be in programs that create large + amounts of long-lived data.</para> + </listitem> </varlistentry> <varlistentry> _______________________________________________ Cvs-ghc mailing list [email protected] http://www.haskell.org/mailman/listinfo/cvs-ghc
