On Mon, Jan 29, 2007 at 05:54:44PM -0400, Luiz Mendes wrote: > On all of my tests write files using MPI_File_write to a current NFS > volume is faster than write to PVFS2.. > > For example, when i increase the number os threads, the bandwith > decreases in both PVFS2 and NFS. > > NFS in the examples have been 20 times faster than PVFS2. > > Is it correct? > > I am using a single computer. In 2 computers the results of PVFS2 is > slower than using one. Am i doing something wrong to measure band? > > I am not using too, pVFS2 kernell module, i am using it by MPI IO and MPI > ROMIO.
Hi Luiz What you describe makes sense: you are probably seeing NFS caching behavior, while PVFS does not cache on clients. If you want to measure the effective bandwidh, you should either - time "open to close" for the two file systems, - or include the time for a call to MPI_File_sync after your last write ==rob -- Rob Latham Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF Argonne National Lab, IL USA B29D F333 664A 4280 315B _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
