How to Open Second Instance of Prime95?

jinydu · 2006-12-24, 09:49

I just installed Prime95 on a dual core computer, and I haven't been able to figure out how to do this.

tha · 2006-12-24, 11:51

Quote:

Originally Posted by jinydu

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.

rx7350 · 2006-12-24, 14:02

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.

tha · 2006-12-24, 18:01

One more thing I haven't been able to manage is to have both copies start up at boot.

potonono · 2006-12-24, 23:51

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]

jinydu · 2006-12-25, 11:10

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.

S485122 · 2006-12-25, 12:54

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 :

both instances use the same affinity,
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,
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.

jinydu · 2006-12-25, 13:42

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.

Prime95 · 2006-12-25, 14:23

Quote:

Originally Posted by jinydu

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

rx7350 · 2007-01-09, 16:00

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.

Prime95 · 2007-01-09, 16:11

Yes, -Ax can be used to start several prime95s. You'll need to set the Affinity from the menus in each prime95 instance.

2006-12-24, 09:49	#1
jinydu Dec 2003 Hopefully Near M48 2×3×293 Posts	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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2006-12-24, 14:02	#3
rx7350 Feb 2006 AR, US 90₁₆ Posts	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.

2006-12-24, 18:01	#4
tha Dec 2002 3·269 Posts	One more thing I haven't been able to manage is to have both copies start up at boot.

2006-12-24, 23:51	#5
potonono Jun 2005 USA, IL 193 Posts	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]

2006-12-25, 11:10	#6
jinydu Dec 2003 Hopefully Near M48 11011011110₂ Posts	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.

2006-12-25, 13:42	#8
jinydu Dec 2003 Hopefully Near M48 2·3·293 Posts	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.

2007-01-09, 16:00	#10
rx7350 Feb 2006 AR, US 2⁴·3² Posts	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.

2007-01-09, 16:11	#11
Prime95 P90 years forever! Aug 2002 Yeehaw, FL 2³·919 Posts	Yes, -Ax can be used to start several prime95s. You'll need to set the Affinity from the menus in each prime95 instance.