We used POSIX_FADV_DONTNEED in distributed iozone test to clear cache on slave client after initial write and before client reads back same data. It helped to see real data rates instead of unrealistically high read rate due do cacheing. Perhaps it was non-lustre (NFS) file server.
If you do scripting, small executable like http://www.citi.umich.edu/projects/asci/benchmarks.html (scroll down to Clearcache) can be called after "cp" or "dd." Alex. On Mar 19, 2011, at 12:47 AM, Jay wrote: > After checking 2.6.35 kernel source code, POSIX_FADV_NOREUSE > actually doesn't do anything. So I don't know how it helps. Probably > we should do POSIX_FADV_DONTNEED after reading? > > Jay > On Mar 18, 2011, at 1:07 AM, DEGREMONT Aurelien wrote: > >>> ... snip... >> Hmm... I do not want to patch 'cp' or 'dd' :) _______________________________________________ Lustre-discuss mailing list Lustre-discuss@lists.lustre.org http://lists.lustre.org/mailman/listinfo/lustre-discuss