mersenneforum.org - View Single Post - How do I get comprehensible MPI behaviour

fivemack · 2011-09-02, 20:38

The problem with process placement is how to get the currently-running processes, and more importantly their memory pages, off the CPUs ... there is probably some simple way, beyond 'for u in $(pidof gnfs-lasieve4I14e); do task set -p ffffff000000 $u; done', of evicting all the processes from half the CPUs (so freeing up two full sockets and eight memory channels for my MPI run), but I have the belief that that will leave the processes using physical memory attached to the empty sockets, so lots and lots of inter-processor traffic.

2011-09-02, 20:38	#3
fivemack (loop (#_fork)) Feb 2006 Cambridge, England 2·3,191 Posts	The problem with process placement is how to get the currently-running processes, and more importantly their memory pages, off the CPUs ... there is probably some simple way, beyond 'for u in $(pidof gnfs-lasieve4I14e); do task set -p ffffff000000 $u; done', of evicting all the processes from half the CPUs (so freeing up two full sockets and eight memory channels for my MPI run), but I have the belief that that will leave the processes using physical memory attached to the empty sockets, so lots and lots of inter-processor traffic.