>Were the benefits coming from extra concurrency (no >single writer lock) or avoiding the extra copy to page cache or >from too much readahead that is not used before pages need to >be recycled.
With QFS, a major benefit we see for databases and direct I/O is an effective doubling of the memory available to the database for caching. Without direct I/O, every page read winds up in the file system cache and the database cache. For large databases, this is the difference between retaining key indexes in memory, or not. (The block copy into user space is also not cheap.) Anton This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
