[commit: ghc] master: Suggest -H to improve GC productivity, fixes #10474. (6adfb88)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/6adfb88a4eb1988d5c674513545280fc66bf1627/ghc

>---------------------------------------------------------------

commit 6adfb88a4eb1988d5c674513545280fc66bf1627
Author: Edward Z. Yang <ezyang at cs.stanford.edu>
Date:   Tue Jun 2 11:07:04 2015 -0700

    Suggest -H to improve GC productivity, fixes #10474.
    
    Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>
    
    Test Plan: none
    
    Reviewers: rwbarton, austin
    
    Subscribers: bgamari, thomie
    
    Differential Revision: https://phabricator.haskell.org/D937
    
    GHC Trac Issues: #10474


>---------------------------------------------------------------

6adfb88a4eb1988d5c674513545280fc66bf1627
 docs/users_guide/sooner.xml | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/docs/users_guide/sooner.xml b/docs/users_guide/sooner.xml
index 68bcc61..41d04dd 100644
--- a/docs/users_guide/sooner.xml
+++ b/docs/users_guide/sooner.xml
@@ -459,11 +459,15 @@ f (Wibble x y)  # ugly, and proud of it
           option</primary></indexterm> RTS option) indicate that it's
           doing lots of garbage-collection (say, more than 20%
           of execution time), more memory might help—with the
-          <option>-M<size></option><indexterm><primary>-M<size>
+          <option>-H<size></option><indexterm><primary>-H<size>
           RTS option</primary></indexterm> or
           <option>-A<size></option><indexterm><primary>-A<size>
           RTS option</primary></indexterm> RTS options (see <xref
-          linkend="rts-options-gc"/>).</para>
+          linkend="rts-options-gc"/>).  As a rule of thumb, try
+          setting <option>-H<size></option> to the amount of memory
+          you're willing to let your process consume, or perhaps try passing
+          <option>-H</option> without any argument to let GHC calculate
+          a value based on the amount of live data.</para>
 	</listitem>
       </varlistentry>
     </variablelist>