Dear Neal!
We are working on Intel quad-core Xeon processors and it's the same. The limiting factor is not the computational power of the processors, it's the interface to the system memory. As in Intel processors all cores share the same front side bus, execution times decrease very little when starting more than one process on the same CPU (not core). Therefore: Buy cheaper but more CPUs! But are there already any experience with the new Intel i7-processors? The memory interface is transferred into the CPU and the bandwidth is tripled. So there should be much better performance with fdtd. Best regards, Roman Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Zheng Li Gesendet: Dienstag, 25. November 2008 02:26 An: neal skinner Cc: meep-discuss Betreff: Re: [Meep-discuss] How do I get meep-mpi to work? neal skinner wrote: Zheng, Lieven, WBR and Fellow MEEP users, Your suggestions were right on the money. When I got rsh enabled and started specifying the full path to meep-mpi, things started working. Unfortunately, I am dissapointed by the decrease in execution times I have experienced so far. For example, the best speed up I have seen is only 10 - 15% when using up to 4 processors. While running on multiple processors, I can go into the system monitor and see multiple instances of meep-mpi and it looks like the memory required for the job is split among these processes, but with no big speed increase. I understand that sometimes MPI does not show any significant decrease in processing times for small problems, so I have tried several sizes of problems - all with similar results. I am not complaining, 10 - 15 % more speed is better than what I had, but I was expecting maybe something like 50% less time required for 4 processors. Do you have any other suggestions that I might try. Once again, I thank you for your help. Best regards, Neal On Wed, Nov 19, 2008 at 11:51 PM, Zheng Li <[EMAIL PROTECTED]> wrote: neal skinner wrote: Zheng, I am running a quad core pentium (Q6600). When I enter rsh localhost, it asks for a password and I get the following: [EMAIL PROTECTED]:~/meep/pec-reflector$ rsh localhost Password: Last login: Wed Nov 19 22:07:49 CST 2008 from localhost on pts/2 Linux blackie 2.6.18-6-amd64 #1 SMP Wed Oct 15 10:07:11 UTC 2008 x86_64 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. You have new mail. [EMAIL PROTECTED]:~$ then, when I type exit, i get [EMAIL PROTECTED]:~/meep/pec-reflector$ ssh localhost ssh: connect to host localhost port 22: Connection refused [EMAIL PROTECTED]:~/meep/pec-reflector$ Nothing much happens with ssh: [EMAIL PROTECTED]:~/meep/pec-reflector$ ssh localhost ssh: connect to host localhost port 22: Connection refused [EMAIL PROTECTED]:~/meep/pec-reflector$ So, I think the conclusion is I can log in with rsh, but not ssh. Thanks again! Neal On Wed, Nov 19, 2008 at 7:48 PM, Zheng Li <[EMAIL PROTECTED]> wrote: neal skinner wrote: Thank you for your help, but I tried your suggestions, and it still does not work. Both mpirun and meep-mpi are in /usr/bin. Here is the response I now get when I add the full path to meep-mpi as well as to mpirun: [EMAIL PROTECTED]:~/meep/pec-reflector$ /usr/bin/mpirun -np 2 /usr/bin/meep-mpi pec-reflector-50.ctl Permission denied. p0_20989: p4_error: Child process exited while making connection to remote process on localhost: 0 p0_20989: (2.007812) net_send: could not write to fd=4, errno = 32 [EMAIL PROTECTED]:~/meep/pec-reflector$ I get a permission denied error message. I get the same message if I sign on as superuser. Any more thoughts on what I can do to get meep-mpi to work? Once again, I thank you in advance of your help. Best regards, Neal On Wed, Nov 19, 2008 at 3:37 AM, Zheng Li <[EMAIL PROTECTED]> wrote: neal skinner wrote: Folks, I have been experimenting with MEEP for several months now and cannot get meep-mpi to work. I am running a quad core Pentium (Q6600) system and think I have downloaded all the right files. When I try to run meep-mpi for two processors this is what I get: [EMAIL PROTECTED]:~/meep/pec-reflector$ mpirun -np 2 meep-mpi pec-reflector-50.ctl Warning: Command line arguments for program should be given after the program name. Assuming that pec-reflector-50.ctl is a command line argument for the program. Missing: program name Program meep-mpi either does not exist, is not executable, or is an erroneous argument to mpirun. I think this error message is saying that meep-mpi is not present, but I can run meep-mpi [EMAIL PROTECTED]:~/meep/pec-reflector$ meep-mpi pec-reflector-50.ctl Using MPI version 1.2, 1 processes ----------- and everything works like normal meep. Obviously I'm missing something somewhere. I am new to Linux and parallel processing, so any help to get me pointed in the right direction would be appreciated. Thanks in advance, Neal _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss Hi, You should tell mpi-run the absolute path or the one relative to the current working path of meep-mpi like mpi-run -np 2 /usr/bin/meep-mpi a.ctl or mpi-run -np 2 ../bin/meep-mpi a.ctl. Yet, when you type meep-mpi in bash/csh, the shell can guess the absolute path for you via searching the paths provided by the environment variable PATH. For example: PATH=~/apps/bin:/usr/local/bin:/usr/bin then bash/csh "tries" ~/apps/bin/meep-mpi, /usr/local/bin/meep-mpi, and /usr/bin/meep-mpi one by one. Once the shell finds meep-mpi, meep-mpi is called. Yours Zheng 2008-11-19 Hi, neal skinner: What linux box and which mpi system do you use. It seems like that you can not login remotely. Try: rsh localhost or ssh localhost Can you successfully login? Zheng 2008-11-20 Since debian uses mpich to compile meep-mpi, there is something wrong with your rsh. See http://www-unix.mcs.anl.gov/mpi/mpich1/docs/faq.htm#permdenied for further informations. Good luck for you. Zheng 2008-11-20 Hi neal You should find the bottleneck by yourself to speed up meep-mpi. Yet, two tools may be useful: a: top/htop to show your CPU and MEM usage; b: sudo iptraf to show your network usage. Zheng 2008-11-25
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