On Thu, Jan 14, 2010 at 7:25 PM, Gus Correa <g...@ldeo.columbia.edu> wrote:
> > First, to test, run HPL in a single node or a few nodes, > using small values of N, say 1000 to 20000. > > The maximum value of N can be approximated by > Nmax = sqrt(0.8*Total_RAM_on_ALL_nodes_in_bytes/8). > This uses all the RAM, but doesn't get into memory paging. > > Then run HPL on the whole cluster with the Nmax above. > Nmax pushes the envelope, and is where your > best performance (Rmax/Rpeak) is likely to be reached. > Try several P/Q combinations for Nmax (see the TUNING file). > Thanks Gus! That helps a lot. I have Linpak running now on just a single server and am trying to tune and hit the Rpeak. I'm getting 62 Gflops but I think my peak has to be around 72 (2.26 GHz 8 cores Nehalem). On a single server test do you manage to hit the theoretical peak?What's a good Rmax / Rpeak to shoot for while tuning? Once I am confident I'm well tuned on one server I'll try and extend it to the whole cluster. -- Rahul _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
