mirror of https://github.com/tLDP/LDP
88 lines
2.9 KiB
Plaintext
88 lines
2.9 KiB
Plaintext
<CHAPTER id="Hints">
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<TITLE>Hints and Tips</TITLE>
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<SECT1><TITLE>Locked Processes</TITLE>
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<PARA>
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If for some reason you find your processes are always locked in
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your home node and you can't find the reason, you can put the
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following lines into your ~/.profile as a stop-gap measure to
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automatically enable migration:
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<PROGRAMLISTING>
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if [ -x /proc/$$/lock ]; then
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echo 0 > /proc/$$/lock
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fi
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</PROGRAMLISTING>
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However, you should make an effort to find out what the problems is
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</PARA>
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</SECT1>
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<SECT1>
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<TITLE>Choosing your processes</TITLE>
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<PARA>
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You will probably want to test your setup before deciding which
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programs you want to enable migration for. For example, if you are
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running KDE2 on a slow machine and have a significantly faster
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machine has part of your Mosix cluster, you might find
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resource-hungry programs like kmail are migrated out. This is not a
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bad thing as such, however, it can lead to a brief moment when your
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writing is not displayed on the screen immediately.
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</PARA>
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</SECT1>
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<SECT1><TITLE> Java and openMosix</TITLE>
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<PARA>
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Green Threads JVM's, allow for migration because each Java thread is a separate process.
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Threads other than Java green thread JVM's cannot be migrated by Linux, so openMosix cannot migrate programs that use them.
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</para>
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<para>
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If you have the source so your Java application you might be able to compile the application native. In this case you might be able to migrate
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your applications to another node.
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</para>
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<para>
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Gian Paolo Ghilardi wrote a paper titled Consideration on OpenMosix it deals amongst other topics with Java an
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dopenMosix.
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<ulink url="
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http://www.democritos.it/events/openMosix/papers/crema.pdf"><citetitle>
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http://www.democritos.it/events/openMosix/papers/crema.pdf</citetitle></ulink>
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</PARA>
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</SECT1>
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<SECT1><TITLE>openMosix and Hyperthreading</title> <para> Basically openMosix
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performance increases with the current Linux scheduler when Hypethreading is
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disabled. You can do this by either entering 'noht' as a boot option or
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disabling HT in the bios.
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</para><para>For those who are still wondering what hypetrheading is :
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<ulink url="http://www.intel.com/technology/hyperthread/"><citetitle>Intel
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explains it</citetitle></ulink>
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</para>
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</sect1>
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<sect1><title>openMosix and Firewalls</title>
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<para>People often have questions regarding openMosix and firewalls.
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Amit helped me out on this matter:
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<programlisting>
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from hpc/comm.c:
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#define MIG_DAEMON_PORT 0x3412
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#define INFO_DAEMON_PORT 0x3415
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</programlisting>
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converted to decimal, they are: 4660 and 5428 resp. (convert 1234, and not
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3412, 'cos of the network-host byte ordering conversions.. Read the
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IP/TCP/UDP RFCs for info)
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</para>
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<para>
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the mig_daemon port is a tcp port, the info_daemon port is udp.
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Hence tcp/4660 and udp/5428, Matt also mentions tcp/723 somewhere.
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</para>
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</sect1>
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</CHAPTER>
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