Processor Affinity

R.D. Silverman · 2011-02-25, 13:58

I am setting up to run ECM in a distributed environment.

I am creating a parent process that gets the hostname, creates
checkpoint and output file names from the hostname, then makes
a call to system() with an appropriately constructed command string
to invoke GMP-ECM.

I would also like to have separate output files for each core when
running on a multi-core system. Otherwise, if I name e.g.
my output files as "hostname.chk" I will get collisions.

Does anyone know of a Windows
system call that will return the processor ID during run-time?
I could then incorporate the processor ID in the output file names.

I tried Google, of course, but can't seem to find/use the right
keywords.

WraithX · 2011-02-25, 14:20

Why not use your "parent process" to pick a unique id and then append that to the chk file?

You could use uid's like {1,2,3,4} and give the checkfile name to gmp-ecm like -chkpnt hostname-1.chk, -chkpnt hostname-2.chk, etc.

Prime95 · 2011-02-25, 14:27

GetAffinityMask tells you which processors your program is allowed to run on. It does not tell you which processor you are currently assigned to. Thus it always returns -1, unless you or someone else has called SetAffinityMask.

GetSystemInfo will return the number of logical processors on the machine.

science_man_88 · 2011-02-25, 14:33

Quote:

Originally Posted by R.D. Silverman

I am setting up to run ECM in a distributed environment.

I am creating a parent process that gets the hostname, creates
checkpoint and output file names from the hostname, then makes
a call to system() with an appropriately constructed command string
to invoke GMP-ECM.

I would also like to have separate output files for each core when
running on a multi-core system. Otherwise, if I name e.g.
my output files as "hostname.chk" I will get collisions.

Does anyone know of a Windows
system call that will return the processor ID during run-time?
I could then incorporate the processor ID in the output file names.

I tried Google, of course, but can't seem to find/use the right
keywords.

I know I'm probably on your ignore list and of no major help but I have a copy of advanced MSDOS which may have something and if not I also use :
http://www.computerhope.com/msdos.htm for windows system commands but I'm not sure how in date these are. wonder if PARI can generate a list of valid commands it allows system calls.

ATH · 2011-02-25, 14:53

You can have one copy of gmp-ecm for each core. Use imagecfg.exe to setup each gmp-ecm to run on a specific core:
http://www.robpol86.com/index.php/ImageCFG

imagecfg.exe -a 0x1 ecm.exe
imagecfg.exe -a 0x2 ecm.exe
imagecfg.exe -a 0x4 ecm.exe
imagecfg.exe -a 0x8 ecm.exe

this setting remains with the ecm.exe until changed with imagecfg or until ecm.exe overwritten by a recompile.

R.D. Silverman · 2011-02-25, 18:22

Quote:

Originally Posted by WraithX

Why not use your "parent process" to pick a unique id and then append that to the chk file?

Reasonable. If you can tell me how a process can pick a unique ID.
One has (say) two processes running. Suppose I generate a PRN based on
(say) microseconds after midnight and use it as an ID. There is no
guarantee that it will be unique. Highly probable, yes. But no guarantee.

Alternately, I could set up an external file:

ID1 flag
ID2 flag
ID3 flag

Where flag = 0 for "ID available". It then gets set to 1 when used.
However, there is no guarantee that two processes won't both read
the same line at the same time.

Quote:

You could use uid's like {1,2,3,4} and give the checkfile name to gmp-ecm like -chkpnt hostname-1.chk, -chkpnt hostname-2.chk, etc.

This is what I intend. Perhaps I might use getpid(). If this were Unix, I would. Is it available under Windows? I don't know nearly as much about
Windows system level coding as I do Unix.

R.D. Silverman · 2011-02-25, 18:24

Quote:

Originally Posted by ATH

You can have one copy of gmp-ecm for each core. Use imagecfg.exe to setup each gmp-ecm to run on a specific core:
http://www.robpol86.com/index.php/ImageCFG

imagecfg.exe -a 0x1 ecm.exe
imagecfg.exe -a 0x2 ecm.exe
imagecfg.exe -a 0x4 ecm.exe
imagecfg.exe -a 0x8 ecm.exe

this setting remains with the ecm.exe until changed with imagecfg or until ecm.exe overwritten by a recompile.

Very Nice! But I am not allowed to download/install code from the net
onto any office machines.

R.D. Silverman · 2011-02-25, 18:35

Quote:

Originally Posted by R.D. Silverman

Reasonable. If you can tell me how a process can pick a unique ID.
One has (say) two processes running. Suppose I generate a PRN based on
(say) microseconds after midnight and use it as an ID. There is no
guarantee that it will be unique. Highly probable, yes. But no guarantee.

Alternately, I could set up an external file:

ID1 flag
ID2 flag
ID3 flag

Where flag = 0 for "ID available". It then gets set to 1 when used.
However, there is no guarantee that two processes won't both read
the same line at the same time.

This is what I intend. Perhaps I might use getpid(). If this were Unix, I would. Is it available under Windows? I don't know nearly as much about
Windows system level coding as I do Unix.

_getpid() does seem to be available under VS C++

wblipp · 2011-02-25, 19:17

Quote:

Originally Posted by R.D. Silverman

I am setting up to run ECM in a distributed environment.

I am creating a parent process that gets the hostname, creates
checkpoint and output file names from the hostname, then makes
a call to system() with an appropriately constructed command string
to invoke GMP-ECM.

Have you considered running an ECMNET server, with one client per core?

xilman · 2011-02-25, 22:00

Quote:

Originally Posted by wblipp

Have you considered running an ECMNET server, with one client per core?

That's exactly what I do here.

Paul

R.D. Silverman · 2011-02-25, 22:53

Quote:

Originally Posted by xilman

That's exactly what I do here.

Paul

I would have to designate a machine to be the server.

I have no way to assure that said machine will be up
at any given time. I am using public machines which are
subject to being disconnected (so others can plug in
their laptop), turned off at the whim of the last one to log in,
etc. etc. Sometimes people disconnect a machine to plug in
their laptop only to fail to restore the connection later.

The only machanism that I have for starting distributed processes
is the Windows task scheduler (equivalent to Unix cron jobs).

Availability of machines is very unreliable.

I can't use my laptop as the server since I often take it home.

2011-02-25, 13:58	#1
R.D. Silverman "Bob Silverman" Nov 2003 North of Boston 2·3,779 Posts	Processor Affinity I am setting up to run ECM in a distributed environment. I am creating a parent process that gets the hostname, creates checkpoint and output file names from the hostname, then makes a call to system() with an appropriately constructed command string to invoke GMP-ECM. I would also like to have separate output files for each core when running on a multi-core system. Otherwise, if I name e.g. my output files as "hostname.chk" I will get collisions. Does anyone know of a Windows system call that will return the processor ID during run-time? I could then incorporate the processor ID in the output file names. I tried Google, of course, but can't seem to find/use the right keywords.

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2011-02-25, 14:20	#2
WraithX Mar 2006 2³·3·23 Posts	Why not use your "parent process" to pick a unique id and then append that to the chk file? You could use uid's like {1,2,3,4} and give the checkfile name to gmp-ecm like -chkpnt hostname-1.chk, -chkpnt hostname-2.chk, etc.

2011-02-25, 14:27	#3
Prime95 P90 years forever! Aug 2002 Yeehaw, FL 2²·5·7·59 Posts	GetAffinityMask tells you which processors your program is allowed to run on. It does not tell you which processor you are currently assigned to. Thus it always returns -1, unless you or someone else has called SetAffinityMask. GetSystemInfo will return the number of logical processors on the machine.

2011-02-25, 14:53	#5
ATH Einyen Dec 2003 Denmark 2·3·5²·23 Posts	You can have one copy of gmp-ecm for each core. Use imagecfg.exe to setup each gmp-ecm to run on a specific core: http://www.robpol86.com/index.php/ImageCFG imagecfg.exe -a 0x1 ecm.exe imagecfg.exe -a 0x2 ecm.exe imagecfg.exe -a 0x4 ecm.exe imagecfg.exe -a 0x8 ecm.exe this setting remains with the ecm.exe until changed with imagecfg or until ecm.exe overwritten by a recompile.