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Old 2009-09-08, 19:04   #1
John Rheinstein
 
Dec 2002

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Default Optimizing Core2 quad in Windows XP

I am running two computers with a Core2 Quad each with Windows XP. I run one exponent test on each core. I am doing a little overclocking.
Is there a way to improve the efficiency by hyper-threading, or something else? If so, how do I implement that. How do I turn on hyper-threading on Win XP?
Thanks
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Old 2009-09-08, 19:08   #2
Uncwilly
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Quote:
Originally Posted by John Rheinstein View Post
I run one exponent test on each core. I am doing a little overclocking.
Is there a way to improve the efficiency by hyper-threading, or something else?
What is your goal? If you want to maximize your total output, do you only care about the L-L testing, or are T-F and P-1 ok too?
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Old 2009-09-08, 19:23   #3
John Rheinstein
 
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I only care about LL testing - and I want to maximize throughput.
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Old 2009-09-08, 20:39   #4
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Fast memory and good timing settings.
Not my area of knowledge.
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Old 2009-09-08, 22:30   #5
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Hyper threading isn't available on the Core2 series - Core i7 cpus have it though. It's a hardware setting. It's generally on by default. Core i7 have a different socket to core2 quads so it isn't a simple upgrade.

-- Craig
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Old 2009-09-09, 01:29   #6
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Quote:
Originally Posted by John Rheinstein View Post
I am running two computers with a Core2 Quad each with Windows XP. I run one exponent test on each core. I am doing a little overclocking.
Is there a way to improve the efficiency by hyper-threading, or something else? If so, how do I implement that. How do I turn on hyper-threading on Win XP?
Thanks
Is your memory and/or motherboard saturated? You might be able to get a little umph by upgrading them but once you start, you might find you'll just want to upgrade the CPU too.
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Old 2009-09-10, 09:35   #7
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I did some extensive benchmarking on a Q6600 and found that running one LL test on a two core pair (1 worker; 2 threads) and two instances gave the best performance for LL testing. I made no attempts to check timings with other combined work types however I did notice that when a P-1 assignment runs on one pair the other pair does slow down slightly which indicates that mixing work types doesn't give increased throughput. Probably an issue with memory speed.
http://www.mersenneforum.org/attachm...entid=2810&d=1

or
http://www.mersenneforum.org/showpos...t=362224347971

Be very careful to assure that Core pairing is rigid. Some Boards seem to return the core identity incorrectly on start-up.

http://www.mersenneforum.org/showthread.php?t=12415
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Old 2009-09-10, 13:10   #8
John Rheinstein
 
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Nelson-

That is very interesting.

How do I set things up to use 2 cores to run a single LL test?

I am running a Q6600 on one system, a Q6700 on another.
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Old 2009-09-10, 15:18   #9
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Quote:
Originally Posted by John Rheinstein View Post
How do I set things up to use 2 cores to run a single LL test?
In Test > Worker Windows, set "CPUs to use (multithreading):" to 2 (for the worker(s) you want to use 2 cores on each LL, of course). If you already have as many worker windows as CPUs/cores, the option will be grayed out and you'll first have to lower the number of workers.

Last fiddled with by Mini-Geek on 2009-09-10 at 15:18
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Old 2009-09-10, 19:38   #10
John Rheinstein
 
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Quote:
Originally Posted by Mini-Geek View Post
In Test > Worker Windows, set "CPUs to use (multithreading):" to 2 (for the worker(s) you want to use 2 cores on each LL, of course). If you already have as many worker windows as CPUs/cores, the option will be grayed out and you'll first have to lower the number of workers.
Many thanks - I got it!
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Old 2009-09-10, 21:51   #11
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Quote:
Originally Posted by Nelson View Post
I did some extensive benchmarking on a Q6600 and found that running one LL test on a two core pair (1 worker; 2 threads) and two instances gave the best performance for LL testing. I made no attempts to check timings with other combined work types however I did notice that when a P-1 assignment runs on one pair the other pair does slow down slightly which indicates that mixing work types doesn't give increased throughput. Probably an issue with memory speed.
Yes, but mixing work types is generally okay if they're really different.

From a CPU's point-of-view, LL and P-1 (and ECM) are almost exactly alike. Both (all three) have a main compute loop which is running FFTs through the FPU as fast as possible. P-1 (or ECM) stage 2 has a much higher memory usage (amount of memory used, not speed of transfer) than LL.

So, basically, the only mix of work types that might be advantageous for throughput is (TF + anything else) -- keeping in mind that two stage 2s (P-1 and/or ECM) might fight each other for real memory.
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