On Tue, Oct 06, 2015 at 12:35:30PM -0700, mathog wrote: > Lately I have been working on a system with >512Gb of RAM and a lot > of processors. > This wouldn't be at all a cost effective beowulf node, but it is a > godsend when the problems being addressed require huge amounts of > memory and do not partition easily to run on multiple nodes.
Yep, many supercomputer bids include a cluster of identical machines, and a couple of large-memory nodes for pre- and post-processing. Might as well stuff as many cpu cores on the large-memory nodes as is cost effective, especially these days were more sockets == more memory. > This machine is also prone to locking up (to the point it doesn't > answer terminal keystrokes from a remote X11 terminal) when writing > huge files back to disk. Watch the number of dirty pages (cat /proc/meminfo | grep Dirty). At blekko we had a "polite writer" routine that inserted short sleeps when Dirty got too high. In theory recent Linux kernels can slow down the correct process that's generating a lot of dirty pages, but in reality it screws up enough that it's smart to have big writers use a polite writer, if you can. -- greg _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
