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Old 2006-12-24, 09:49   #1
jinydu
 
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Default How to Open Second Instance of Prime95?

I just installed Prime95 on a dual core computer, and I haven't been able to figure out how to do this.
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Old 2006-12-24, 11:51   #2
tha
 
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Quote:
Originally Posted by jinydu View Post
I just installed Prime95 on a dual core computer, and I haven't been able to figure out how to do this.
One way to do it:

Create two directories, Prime95-0 and Prime95-1 and install Prime95 in both directories. Then go to the menu option 'Advanced | Affinity' in both instances and set 'Affinity' to 0 respectively 1. Then let both instances join PrimeNet or feed them manual assignments.

Notice that the 'Options | Torture Test' doesn't work correctly on multi core systems.
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Old 2006-12-24, 14:02   #3
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Another way to do it: Start a first instance in the usual way. Start a second instance by issuing the command 'Prime95 -A1' at a Windows command prompt, and both instances will create their worktodo, results, etc, files in the same Prime95 directory. The affiniities should be set to '0' for one instance, and '1' for the other instance.
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Old 2006-12-24, 18:01   #4
tha
 
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One more thing I haven't been able to manage is to have both copies start up at boot.
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Old 2006-12-24, 23:51   #5
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I think another thread indicated two copies can't both be run as a service, but I'm to lazy to search. I think the options left are as follows:

On the only dual core machine I have, since I'm the only user, I just have shortcuts to both copies in my "%userprofile%\Start Menu\programs\Startup" folder. I could have also placed shortcuts in the "%allusersprofile%\Start Menu\programs\Startup" folder for each Prime95 program. When logging in, any shortcuts there are executed. [Click on Start -> Run and copy/paste the indicated folder locations with or without the quotation marks]

If you want programs to start at bootup, I believe you can create registry entries in the "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" folder to each program, and that would execute them at boot. [Start -> Run and type in regedit]

You could probably also add entries into the autoexec.bat or similar files. [Start -> Run and type in sysedit]
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Old 2006-12-25, 11:10   #6
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I searched through Prime95 Help and found an obscure page that showed how to get a second instance running using DOS. The good news is that both instances run automatically upon boot-up. The bad news is that the second instance has a markedly slower iteration time, even though the FFT size is the same for both tests.
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Old 2006-12-25, 12:54   #7
S485122
 
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One way to do this from one directory only is to create the two services... For MS Windows XP :
Code:
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-0]
"Type"=dword:00000110
"Start"=dword:00000002
"ErrorControl"=dword:00000001
"ImagePath"=hex(2):43,00,3a,00,5c,00,50,00,72,00,6f,00,67,00,72,00,61,00,6d,00,\
  20,00,46,00,69,00,6c,00,65,00,73,00,5c,00,50,00,72,00,69,00,6d,00,65,00,39,\
  00,35,00,5c,00,50,00,72,00,69,00,6d,00,65,00,39,00,35,00,2e,00,65,00,78,00,\
  65,00,00,00
"DisplayName"="Prime95 Service-0"
"ObjectName"="LocalSystem"
"Description"="GIMPS client to find large prime numbers"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-0\Enum]
"0"="Root\\LEGACY_PRIME95_SERVICE-0\\0000"
"Count"=dword:00000001
"NextInstance"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-0\Security]
"Security"=hex:01,00,14,80,90,00,00,00,9c,00,00,00,14,00,00,00,30,00,00,00,02,\
  00,1c,00,01,00,00,00,02,80,14,00,ff,01,0f,00,01,01,00,00,00,00,00,01,00,00,\
  00,00,02,00,60,00,04,00,00,00,00,00,14,00,fd,01,02,00,01,01,00,00,00,00,00,\
  05,12,00,00,00,00,00,18,00,ff,01,0f,00,01,02,00,00,00,00,00,05,20,00,00,00,\
  20,02,00,00,00,00,14,00,8d,01,02,00,01,01,00,00,00,00,00,05,0b,00,00,00,00,\
  00,18,00,fd,01,02,00,01,02,00,00,00,00,00,05,20,00,00,00,23,02,00,00,01,01,\
  00,00,00,00,00,05,12,00,00,00,01,01,00,00,00,00,00,05,12,00,00,00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-1]
"Type"=dword:00000110
"Start"=dword:00000002
"ErrorControl"=dword:00000001
"ImagePath"=hex(2):43,00,3a,00,5c,00,50,00,72,00,6f,00,67,00,72,00,61,00,6d,00,\
  20,00,46,00,69,00,6c,00,65,00,73,00,5c,00,50,00,72,00,69,00,6d,00,65,00,39,\
  00,35,00,5c,00,50,00,72,00,69,00,6d,00,65,00,39,00,35,00,2e,00,65,00,78,00,\
  65,00,00,00
"DisplayName"="Prime95 Service-1"
"ObjectName"="LocalSystem"
"Description"="GIMPS client to find large prime numbers"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-1\Enum]
"0"="Root\\LEGACY_PRIME95_SERVICE-1\\0000"
"Count"=dword:00000001
"NextInstance"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Prime95 Service-1\Security]
"Security"=hex:01,00,14,80,90,00,00,00,9c,00,00,00,14,00,00,00,30,00,00,00,02,\
  00,1c,00,01,00,00,00,02,80,14,00,ff,01,0f,00,01,01,00,00,00,00,00,01,00,00,\
  00,00,02,00,60,00,04,00,00,00,00,00,14,00,fd,01,02,00,01,01,00,00,00,00,00,\
  05,12,00,00,00,00,00,18,00,ff,01,0f,00,01,02,00,00,00,00,00,05,20,00,00,00,\
  20,02,00,00,00,00,14,00,8d,01,02,00,01,01,00,00,00,00,00,05,0b,00,00,00,00,\
  00,18,00,fd,01,02,00,01,02,00,00,00,00,00,05,20,00,00,00,23,02,00,00,01,01,\
  00,00,00,00,00,05,12,00,00,00,01,01,00,00,00,00,00,05,12,00,00,00
jinydu if your second instance has slow iteration times there are three possible causes :
  1. both instances use the same affinity,
  2. both are doing stage 2 of P-1 factoring and the second instance does not have enough memory with memory swapping to disk as a result,
  3. you do not have two cores but hypertheading or you have 2 cores with hyperthreading. To check this last possibility (2 cores with HT) start the taskmanager and check the number of CPUs, if there are four set the affinity of one instance of prime95 to 0 and the second to 2 or disable hyper threading...
On my two core machine the instances perform at the same speed as it should.
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Old 2006-12-25, 13:42   #8
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I discovered the reason for the slowdown, and it is quite unexpected. Apparently, the FFT size is larger for the second instance than the first. Previously, I had already thought of this possibility, but I dismissed it after testing the FFT sizes on another computer. Little did I know that the FFT size limits changed between version 24.13 and version 24.14.
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Old 2006-12-25, 14:23   #9
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Quote:
Originally Posted by jinydu View Post
the second instance has a markedly slower iteration time, even though the FFT size is the same for both tests.
I had the same problem in 64-bit Windows (dual core Pentium 4). It turns out to be some weird Windows problem reading the time stamp counter. I "fixed" it by adding the /usepmtimer to the boot.ini file
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Old 2007-01-09, 16:00   #10
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Can four instances be started on a quad-core cpu using the same methods as previousy mentioned in this thread? I have heard that XP Home doesn't even recognize more than two cores, but that XP Pro does recognize more than two cores, but doesn't distribute 'loads' evenly across the four cores. I'm hoping that using the '-Ax' parameter will force four instances of Prime95 to run, each in it's own core, assuming the affinities can be set to 0, 1, 2, and 3.
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Old 2007-01-09, 16:11   #11
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Yes, -Ax can be used to start several prime95s. You'll need to set the Affinity from the menus in each prime95 instance.
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