wiki:LinuxPMIFAQ

Frequently Asked Questions

If you don't see your question answered here, bug us on the Mailing List or check in with us on IRC!

Q: Is LinuxPMI like OpenMosix?
A: LinuxPMI is a continuation of the 2.6 branch of OpenMosix. this branch was very different from the 2.4 series.
Q: Is LinuxPMI SSI(single system image) software?
A: No. LinuxPMI is multi-system-image software. it looks like SSI, but from the perspective of *each* *node*. LinuxPMI can work in clusters with a diverse choice in linux distributions, libraries, etc. the only thing that must remain the same are CPU types, and some OS kernel features.
Q: Is the latency of network computing worth it for the extra resources?
A: This depends heavily on the communication required between processes to perform a given amount of work.
Q: Would normal applications benefit from this?
A: It heavily depends on the programming style and features used by the application in question. if the application is using features such as shared memory, or threading, the answer is likely 'not without a rewrite'.
Q: What happens if code like parcon.c (parallel port control routines accessing I/O ports directly) migrates?
A: It won't. That's a privileged instruction, and as such, the process will get marked to stay home with flag DSTAY_PRIV. If it opens on remote, it will be migrated home.
Q: What happens when you migrate a task marked with a realtime priority?
A: We won't. Having a realtime priority is one of the 9 reasons a process is un-migratable (including DSTAY_PRIV from above).
Q: How can I communicate between migratable processes?
A1: Use Unix pipes. You can create pipes with dup(2), fork, and then use those pipes to maintain communication between your processes. This Guide to IPC has more details. This is similar to a technique commonly used on OpenMosix 2.4. A2: Depends on what you need done. Just make sure you avoid the reasons a process is un-migratable.
Last modified 8 years ago Last modified on Nov 27, 2013, 7:48:53 AM