Messages in this thread | | | From | (Larry McVoy) | Subject | Re: Lets get this right (WAS RE:MOSIX and kernel mods) | Date | Sun, 07 Mar 1999 00:10:45 -0800 |
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: Just how smart have they made this optimisation, BTW? For the volume : rendering application, you have two conceptual transfers of data: the : volume data is "shipped" to worker nodes and they in turn "ship" : subimage data back to the scheduling node.
If I recall correctly, they actually wacked the OS. They used /proc and made a way that another process could map a different process' address space. Sends can be implemented, on page sized quantities, as mapping a page COW into another process' address space.
Zero copy for big data that wasn't touched, otherwise copy on write.
For small data, it was just a copy and a wakeup.
I may have the details wrong, but the bottom line was that MPI went very, very fast - customers were quite amazed and very pleased. It exceeded their expectations.
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