I noticed a strange thing with df.

I deleted a very huge file which was using about 60% of a partition
space.
After a while I did re-run df to see how much disk space I saved, but it
didn't show me updated informations. It still showed a 90% of partition
usage.
I guess this is due to the file system caching mechanism... so, is it
normal? Is there a way to force df to flush the cache?

Thanks
--
  Dante_