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Old 2006-09-20, 18:30   #1
paulunderwood
 
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Default HT processors

Thanks to our latest member, arminius, it has been shown that running two instance of LLR (321) improves throughput. All you need to do is create a new directory/folder (called llr2 or whatever) and run the second instance from there. You will have to have a HT enabled processor and motherboard (and SMP kernel if linux.)

I am unsure about a 533FSB motherboard which is HT but with a 533FSB northwood. It is upto you to do your own tests...

This might help:
http://en.wikipedia.org/wiki/Pentium_4
http://en.wikipedia.org/wiki/Pentium_D

Good luck!

Last fiddled with by paulunderwood on 2006-09-20 at 18:31
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Old 2006-09-21, 14:03   #2
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Quote:
Originally Posted by paulunderwood View Post
Thanks to our latest member, arminius, it has been shown that running two instance of LLR (321) improves throughput. All you need to do is create a new directory/folder (called llr2 or whatever) and run the second instance from there. You will have to have a HT enabled processor and motherboard (and SMP kernel if linux.)

I am unsure about a 533FSB motherboard which is HT but with a 533FSB northwood. It is upto you to do your own tests...

This might help:
http://en.wikipedia.org/wiki/Pentium_4
http://en.wikipedia.org/wiki/Pentium_D

Good luck!
wHAT ABOUT amd x2?
Luigi

Last fiddled with by ET_ on 2006-09-21 at 14:04
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Old 2006-09-21, 15:03   #3
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Presumably, with a dual-core HT chip, you could run 4 instances for maximum throughput. I don't have such a chip. For testing, if you create 4 (321) LLR directories with exactly the same test numbers in each, then check 2 instances running and see if the iteration time is less than double when 4 instances are running (at all times letting the iteration times settle down at say 1000 iterations per screen output.)

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Old 2006-09-21, 15:28   #4
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Here is are results for 3.4Ghz Northwood:

single LLR:
3*2^2827583-1 is not prime. LLR Res64: AFC6CD0A3099B096 Time : 10972.677 sec.

two LLRs:
3*2^2827658-1 is not prime. LLR Res64: FD4EBE816264EF1C Time : 20796.945 sec.

Allowing for a slight variation because these numbers are not exactly the same, that's:
? 2*10972.677/20796.945
1.055220081603331643181246091

a 5.5% gain.

(I wish I had realised this a few years back )

Last fiddled with by paulunderwood on 2006-09-21 at 15:29
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Old 2006-09-21, 15:58   #5
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Quote:
Originally Posted by paulunderwood View Post
(I wish I had realised this a few years back )
New members - new ideas Seriously, I'm glad to see thats working.
a.
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Old 2007-02-15, 13:07   #6
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I did some tests.

I have a Prescott Pentium4 @3,2 GHz and an AMD64 X2 @ 2.0 GHz, both with 1 GB of RAM.

I am running a copy of Prime95 and a copy of LLR 3.7.0 on both machines.

Both fftlen are 163840.

The timing on the AMD64 X2 is exactly ONE HALF the timing of the Pentium4: LLR runs TWICE as fast on AMD64 X2 on the same configuration with another instance of Prime95 running.

Luigi

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Old 2007-02-15, 13:34   #7
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Luigi, I'm not sure whether I fully understand your results.

If I remember correctly, the Prescott is a single-core HT cpu while the Athlon64 X2 is a true dual-core cpu. Therefore you could run two instances of LLR or Prime95 with almost no impact to each other on the Athlon64 X2. But if you do the same on a single-core (HT or not HT doesn't matter really much), each instance would run only at half the speed...

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Old 2007-02-15, 15:47   #8
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Quote:
Originally Posted by Thomas11 View Post
Luigi, I'm not sure whether I fully understand your results.

If I remember correctly, the Prescott is a single-core HT cpu while the Athlon64 X2 is a true dual-core cpu. Therefore you could run two instances of LLR or Prime95 with almost no impact to each other on the Athlon64 X2. But if you do the same on a single-core (HT or not HT doesn't matter really much), each instance would run only at half the speed...
I lost my mind somewhere else, sorry...

Hyperthreaded CPUs and dual core ones show equal notation on task manager, and I had switched off my brain before writing.

Oh, well shat hippens...

Luigi
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