master 5c532fe303: Recommend that the user turn off memory overcommit

[Po Lu]

branch: master
commit 5c532fe30305393079674557256dbb96253fd517
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Recommend that the user turn off memory overcommit
    
    * doc/emacs/trouble.texi (Memory Full): Tell the user that Emacs
    behaves best with overcommit off, and how to turn it off.
---
 doc/emacs/trouble.texi | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/doc/emacs/trouble.texi b/doc/emacs/trouble.texi
index 93f9c779db..f524a82022 100644
--- a/doc/emacs/trouble.texi
+++ b/doc/emacs/trouble.texi
@@ -296,6 +296,20 @@ editing in the same Emacs session.
 out of memory, because the Buffer Menu needs a fair amount of memory
 itself, and the reserve supply may not be enough.
 
+@cindex memory trouble, GNU/Linux
+  On GNU/Linux systems, the system does not normally report running
+out of memory to Emacs, and can instead randomly kill processes when
+they run out of memory.  We recommend that you turn this behavior off,
+so that Emacs can respond correctly when it runs out of memory, by
+becoming the super user, editing the file @code{/etc/sysctl.conf} to
+contain the following lines, and then running the command @code{sysctl
+-p}:
+
+@example
+vm.overcommit_memory=2
+vm.overcommit_ratio=0
+@end example
+
 @node Crashing
 @subsection When Emacs Crashes