Re: (jeffa) Re: Threading a job between multiple machines

[SyN/AcK]

Aha, well that is cool, I was wondering how SETI worked. So, with threading then, we talked before I believe about the advantages it provided. Say I wanted to thread a job on my machine, does it gain any speed if I'm on a single processor? I believe you told me it wouldn't, but I was thinking in terms of say I was transfering a file, and I made multiple threads to support multiple connections to the file in the hopes of maximizing my bandwidth usage to get the file. Is this reasonable? Or is the speed increase negligable?

What about how they do those distributed attacks of an encryption algorithm? You know what I'm talking about here? They get those large groups of people all over then have some sort of controlling program that tells each machine what key to try... sort of like distributed computing... is this done with threads, or message passing like you mentioned?

Sorry, I'm a n00b in this area.

[jeffa]

IO bound problems benefit from threads on single proc machines. The idea is that if you are waiting on IO, but have other stuff you can be doing in the meantime, then you should be able to spawn a thread to handle the waiting and see 'speed up'. If this is what you want, then i recommend POE (which uses cooperative multitasking ... not threads).

As for your second question ... again, no threads are needed. The clients may run 'in the background' via threads, but UNIX systems have these things called processes which are basically 'heavyweight threads' (threads are really just 'lightweight processes'). The client runs 'in the background' and simply connects to the server on some port when it needs to convey information. This could be construed as 'message passing', and it is, but this really is not the same as message passing on something like a Beowulf Cluster.

Since you are a graduate student, is there perhaps a parallel processing class you can sign up for? You really should get some 'classic training' on this stuff if it is readily available to you.

jeffa

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(the triplet paradiddle with high-hat)