Processes and nodes?

[splayer]

"Suppose you want to configure the parallel engine to recognize an eight-CPU SMP, for example, as two or more processing nodes. When you configure the SMP as two separate processing nodes, the parallel engine creates two processes per stage on the SMP. For a 3 stage job, configuring an SMP as more than two parallel engine processing nodes creates at least 9 UNIX processes, although only eight CPUs are available."

a) How are 9 UNIX processes created? 8 CPUs, 2+ nodes, may be 3. 3 processes per node. So at least 9, right?
b) When we talk about an UNIX process, aren't we talking about an operating system thread?

Thanks to anyone who responds.

[felixyong]

"Suppose you want to configure the parallel engine to recognize an eight-CPU SMP, for example, as two or more processing nodes. When you configure the SMP as two separate processing nodes, the parallel engine creates two processes per stage on the SMP. For a 3 stage job, configuring an SMP as more than two parallel engine processing nodes creates at least 9 UNIX processes, although only eight CPUs are available."

a) How are 9 UNIX processes created? 8 CPUs, 2+ nodes, may be 3. 3 processes per node. So at least 9, right?
b) When we talk about an UNIX process, aren't we talking about an operating system thread?

Thanks to anyone who responds.

Hi

Nodes are related to the partition that is going to create and it is logical which means it may not necessary be equal to physical CPU.

Take a simple example of SeqFile -> Tranform -> SeqFile in a 4 nodes setup. How many processes do you think it will create? 1 + 4 + 1 = 6.

From the Score you can actually identify the number of process that it is going to create.

Nowsaday the CPU is no more Single Core/Thread, anyway. Sometime it is ok to have more processes than CPU just to keep them busy as they're much too faster when compare to Memory or HDD(I/O).[/img]