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Andy

Mon Nov 25 2013, 06:40AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Hi
I'm writing a program and would like to find the fast platform. The code has if statement and alot of branching, not many for loops, but alot of basic blocks that are the same.

Was thinking of using omp on the cpu, as I don't think the graphics card would speed up the code?, is fpga good or do the branch's slow it down?
What about 1000 pics or audino?

Thanks

Carbon_Rod

Mon Nov 25 2013, 07:27AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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For some small platforms, people will dedicate FPGA space to kernel modules that solve specific problems efficiently in parallel.

OpenCL is part of the nVidia SDK, but whether it runs "faster" depends on the problem. A 24+ core multi-cpu machine will churn through data more quickly given it doesn't need to copy into GPU memory space. However, the same machine can not match 400+ 1.8 GHz dedicated gpu vector cells running in parallel.
OpenMP is fine when the problem can be broken apart, and doesn't need set locality in the cluster host partition slice. But in other situations... it can run "slower" than even a single core.

Note it takes far less time to learn Intel's Threading Building Blocks libraries and proper algorithm design...
A good compiler will usually in-line small functions to exploit pipelining.

The "Cloud" demand has shifted technologies into a new class of design problem.
This code example is very helpful in learning about these new paradigms:

Andy

Tue Nov 26 2013, 01:35AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

I don't mind purchasing the hardware(would like to), but don't want to send it into the cloud.
What info do you need?

Carbon_Rod

Tue Nov 26 2013, 09:06AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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Posts: 1155

Describe big Theta, start here:

Read:

Boost:

STL:

Andy

Tue Nov 26 2013, 11:37PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Thanks Carbon_Rod
Got rid of most of the if statements and replaced it with a lookup table. Have you got any information on severs racks, do you set them up like a desktop? or do you think that a gaming rig would be a better option.

Carbon_Rod

Wed Nov 27 2013, 06:59AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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A reliable rack server costs a bit more as they use special parity checked dram to detect errors, reliable Intel CPUs, and have several management options most people never encounter. If you already have a SAN, than the incremental cost of adding cores is minimal. There are also special GPU modules for this type of server, but they're not really useful for the task of serving files.

Desktops have some advantages as they are inexpensive if purchased used, and have more space for random parts. The low-end $50 GeForce GTX 295 is a great deal thanks to Microsoft, as they no longer really work for modern games and the linux CUDA developer drivers are mature for these cards. Note, don't bother putting more than 1 GPU card in a machine, and use at least a â€œ750â€ watt power supply.

Hosts with an older Intel quad run these cards just fine, as do the 24 core >i7 workstations...
Ignore modern sleaze-box labels, and use a benchmark cpu list when buying.

You will find a discrepancy between value and performance in modern retail outlets.

What problem are you trying to solve?

Andy

Wed Nov 27 2013, 07:51AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Its a chemical finder type program, I have to bruteforce alot of combinations, checked out a desktop motherboard with four sockets that can handle amd opteron 12core, but that and ram would set the price at 6 grand....so still dreaming, that would take 4 hours for 500 chemical combinations, hopefully looking at 100million combinations...

With graphics cards do you get a lower performance with if and for loops? I can unroll some of the for loops. Last time I tryed to write a kernel for a Gcard it wasn't much faster than cpu, could you post or link to a good reference of how to program them.

Thanks for your help

Shrad

Wed Nov 27 2013, 08:14AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
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Posts: 780

have a look at blade servers, they provide multi cpu and RAM with a small form factor and a much smaller than the desktop multi cpu units

Andy

Wed Nov 27 2013, 10:15AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

There was a 8 core 1 socket for $1000, still haven't ruled out grahics cards, or pics the code could fit on a 32bit pic easly , maybe have a pic with 2gig sdcard with another layer for the second stage processing, $1000 dollars would give 1k cores, do able?

Shrad

Wed Nov 27 2013, 12:02PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
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Posts: 780

you would have to add some RAM or you will eat through read/write cycles of your SD card pretty quickly

maybe with playstations or something alike? I read somewhere you could install unix on some playstation 2 or 3 or xbox, I don't remember

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