On Tuesday 14 February 2006 11:25, Miguel Martinez wrote: > I'm running parallel espresso (v2.1.5) in an Itanium2 cluster [...] > Most nodes use 4Gb, though there are some with 16Gb RAM. > > The thing is that, when I send a phonon multiprocessor run, while it > doesn't use a lot of memory (some 250Mb per thread), it swaps out. > I've run two processors in a 4 proc node and, to make sure other > jobs don't interfere, using all 4 procs for myself.
if you really use 2*250Mb out of 4Gb, you will not swap, unless your machine is horribly loaded. If you are swapping, you are using more memory than you think. How did you get that number? it is not easy to know how much memory a process is really using. Also note that some recent versions of the code contain rather large statically allocated arrays that are not distributed across processors (i.e. each process has its own copy). Check with command "size ph.x" how big is the so-called "bss". Most of that memory should have been eliminated by now. > I personally haven't seen this on my laptop (gfortran instead of ifc)... you mean g95, or really gfortran? these are two distinct projects > 2) Will this affect performance badly? if you swap all the time, it will, for sure > 3) This is a bit off topic. Is it OK to use -npools while using > processors in the same node or is it dumb? it is ok, but it won't save any memory: each process will allocate the entire memory Paolo -- Paolo Giannozzi e-mail: giannozz at nest.sns.it Scuola Normale Superiore Phone: +39/050-509876, Fax:-563513 Piazza dei Cavalieri 7 I-56126 Pisa, Italy
