On Fri, 10 Jul 2009, Roland Mainz wrote:
- "tail" _may_ now be a bit slower since it no longer uses |mmap()| (which was one of the root causes for crashes (e.g. if the underlying file shrinks while "tail" reads it)) - some commands like "join" should be faster now since it uses |mmap()| (but we have an option to turn this behaviour off to avoid running into the issue described with "tail" above)
Perhaps you did not notice the recent discussion on the zfs-discuss list where it was revealed that I/O using mmap() on zfs can be expected to be slower since ZFS uses an ARC rather than the Solaris unified page cache, and therefore there needs to be extra processing/logic to reconcile the two, and there may be double the memory consumption as well.
Once a file has been touched by mmap(), it remains slower as long as pages referencing it remain somewhere in memory. You can easily measure this effect for yourself.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org
