On Mar 20, 2008 18:32 -0400, Mark Seger wrote: > >> As a final note, I've put together a tutorial on using collectl in a > >> lustre environment and have upload a preliminary copy at > >> http://collectl.sourceforge.net/Tutorial-Lustre.html in case anyone > >> wants to preview it before I link it into the documentation. > >> If nothing else, look at my very last example where I show what you > >> can see by monitoring lustre at the same time as your network > >> interface. > > > > Very good, thanks for this. The readahead experiment is insightful. > > > It was to me when I first encountered the problem.
This is a very interesting example, and I wish we had known about collectl a year ago before we invested time in writing data gathering scripts which aren't as useful as what you have here. One question - is this "over readahead" still a problem? I know there was an but like this (anything over 8kB was considered to be sequential and invoked readahead because it generated 3 consecutive pages of IO), but I thought it had been fixed some time ago. There is a sanity.sh test_101 that exercises random reads oand checks that there are no discarded pages. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. _______________________________________________ Lustre-discuss mailing list Lustre-discuss@lists.lustre.org http://lists.lustre.org/mailman/listinfo/lustre-discuss