thank you for your detailed analysis. your guess is right .my outdir is set to a place,not local to the nodes.i know the reason of my slow job,although i did not know it through. as for how to use a local directory as outdir ,it seems another new thing for me. would it be possible to tell me about that ? thank you in advance
your sincerely xuyuehua 2007/12/13, Lorenzo Paulatto <paulatto at sissa.it>: > > > On Thu, December 13, 2007 13:42, xu yuehua wrote: > > yes,maybe once i set disk_io="none" ,when something goes wrong ,like > > power > > is off suddenly,you have to start from scratch .from this point ,it is > > wasting time in deed. > > but is there an better idea ? > > i am wondering > > I think it is highly unlikely that you have more RAM than disk space, so > disk space should be no issue. Furthermore it should not be so slow, as > long as you are leaving wfc_collect=.false. which is the default. > > From these assumptions I can guess that you are using a network share as > temporary directory for your calculation; in other words your outdir is > set to some place, probably in you home directory, which is not local to > nodes but stays on a server and is shared via NFS (network file system). > > If this is your case, every time wavefunctions are written the data has to > pass trough the network, it is somehow equivalent to collect_wfc=.true. > but done externally by the operating system. Furthermore if you are using > the same network for NFS and mpi when the traffic from NFS suddenly bursts > it is likely to conflict with mpi and slow it down a lot. > > To avoid this problem you must use a local directory as outdir (like > /tmp), but you to have to remember that if you want to restart a job you > have to use exactly the same node you used before in order for them to > find their wavefunctions. Otherwise you may have to recollect the data by > hand, which is probably not trivial (I have never tried). > > I hope what I wrote was not already known to you, goodbye. > -- > Lorenzo Paulatto > +39 040 3787 511 > http://people.sissa.it/~paulatto/ > > > ---------------------------------------------------------------- > SISSA Webmail https://webmail.sissa.it/ > Powered by SquirrelMail http://www.squirrelmail.org/ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Xu Yuehua physics Department of Nanjing university China -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20071213/f27b3989/attachment.htm
