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diff --git a/sag-0.6.1-www/Invisible/sag-0.6/node62.html b/sag-0.6.1-www/Invisible/sag-0.6/node62.html new file mode 100644 index 0000000..3cf8f07 --- /dev/null +++ b/sag-0.6.1-www/Invisible/sag-0.6/node62.html @@ -0,0 +1,104 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> +<!--Converted with LaTeX2HTML 96.1-h (September 30, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --> +<HTML> +<HEAD> +<TITLE>Using a swap space</TITLE> +<META NAME="description" CONTENT="Using a swap space"> +<META NAME="keywords" CONTENT="sag"> +<META NAME="resource-type" CONTENT="document"> +<META NAME="distribution" CONTENT="global"> +<LINK REL=STYLESHEET HREF="sag.css"> +</HEAD> +<BODY LANG="EN" > + <A NAME="tex2html1094" HREF="node63.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1092" HREF="node59.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1086" HREF="node61.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1096" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1097" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1095" HREF="node63.html">Sharing swap spaces with </A> +<B>Up:</B> <A NAME="tex2html1093" HREF="node59.html">Memory Management</A> +<B> Previous:</B> <A NAME="tex2html1087" HREF="node61.html">Creating a swap space</A> +<BR> <P> +<H1><A NAME="SECTION00630000000000000000">Using a swap space</A></H1> +<P> + An initialized swap space is taken into use with <tt>swapon</tt><A NAME="1904"> </A>. + This command tells the kernel that the swap + space can be used. The path to the swap space is given as + the argument, so to start swapping on a temporary swap + file one might use the following command. + <BLOCKQUOTE> <TT> +<code>$</code> <I>swapon /extra-swap</I> <BR> +<code>$</code> + </TT></BLOCKQUOTE> + Swap spaces can be used automatically by listing them in + the <tt>/etc/fstab</tt><A NAME="1906"> </A> file. + <BLOCKQUOTE> <TT> +<code>/dev/hda8 none swap sw 0 0</code> <BR> +<code>/swapfile none swap sw 0 0</code> + </TT></BLOCKQUOTE> + The startup scripts will run + the command <tt>swapon -a</tt>, which will start swapping on + all the swap spaces listed in <tt>/etc/fstab</tt><A NAME="1908"> </A>. Therefore, + the <tt>swapon</tt><A NAME="1910"> </A> command is usually used only when extra swap + is needed. +<P> + You can monitor the use of swap spaces with <tt>free</tt><A NAME="1912"> </A>. + It will tell the total amount of swap space used. + <BLOCKQUOTE> <TT> +<code>$</code> <I>free</I> <BR> +<code> total used free shared buffers</code> <BR> +<code>Mem: 15152 14896 256 12404 2528</code> <BR> +<code>-/+ buffers: 12368 2784</code> <BR> +<code>Swap: 32452 6684 25768</code> <BR> +<code>$</code> + </TT></BLOCKQUOTE> + The first line of output (<code>Mem:</code>) shows the physical memory. + The total column does not show the physical memory used by the + kernel, which is usually about a megabyte. The used column shows + the amount of memory used (the second line does not count buffers). + The free column shows completely unused memory. The shared column shows + the amount of memory shared by several processes; the more, the merrier. + The buffers column shows the current size of the disk buffer cache. +<P> + That last line (<code>Swap:</code>) shows similar information for the swap + spaces. If this line is all zeroes, your swap space is not activated. +<P> + The same information is available via <tt>top</tt><A NAME="1914"> </A>, + or using the <tt>proc</tt> filesystem in file <tt>/proc/meminfo</tt><A NAME="1916"> </A>. + It is + currently difficult to get information on the use of a specific + swap space. +<P> + A swap space can be removed from use with <tt>swapoff</tt><A NAME="1918"> </A>. + It is usually not necessary to do it, except for temporary + swap spaces. + Any pages in use in the swap space are swapped in first; if + there is not sufficient physical memory to hold them, they will + then be swapped out (to some other swap space). + If there is not enough virtual memory to hold all of the pages + Linux will start to thrash; after a long while it should + recover, but meanwhile the system is unusable. You should + check (e.g., with <tt>free</tt><A NAME="1920"> </A>) that there is enough free + memory before removing a swap space from use. +<P> + All the swap spaces that are used automatically with + <tt>swapon -a</tt> can be removed from use with <tt>swapoff -a</tt>; + it looks at the file <tt>/etc/fstab</tt><A NAME="1922"> </A> to find what to remove. + Any manually used swap spaces will remain in use. +<P> + Sometimes a lot of swap space can be in use even though there + is a lot of free physical memory. This can happen for instance + if at one point there is need to swap, but later a big process + that occupied much of the physical memory terminates and + frees the memory. The swapped-out data is not + automatically swapped in until it is needed, so the physical + memory may remain free for a long time. There is no need to + worry about this, but it can be comforting to know what is + happening. +<P> +<HR><A NAME="tex2html1094" HREF="node63.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1092" HREF="node59.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1086" HREF="node61.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1096" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1097" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1095" HREF="node63.html">Sharing swap spaces with </A> +<B>Up:</B> <A NAME="tex2html1093" HREF="node59.html">Memory Management</A> +<B> Previous:</B> <A NAME="tex2html1087" HREF="node61.html">Creating a swap space</A> +<P><ADDRESS> +<I>Lars Wirzenius <BR> +Sat Nov 15 02:32:11 EET 1997</I> +</ADDRESS> +</BODY> +</HTML> |