On Tue, 2004-03-02 at 09:34, Peter Nelson wrote: > Hans Reiser wrote: > > I'm confused as to why performing a benchmark out of cache as opposed to > on disk would hurt performance?
My understanding (which could be completely wrong) is that reieserfs v3 and v4 are algorithmically more complex than ext2 or ext3. Reiserfs spends more CPU time to make the eventual ondisk operations more efficient/faster. When operating purely or mostly out of ram, the higher CPU utilization of reiserfs hurts performance compared to ext2 and ext3. When your system I/O utilization exceeds cache size and your disks starting getting busy, the CPU time previously invested by reiserfs pays big dividends and provides large performance gains versus more simplistic filesystems. In other words, the CPU penalty paid by reiserfs v3/v4 is more than made up for by the resultant more efficient disk operations. Reiserfs trades CPU for disk performance. In a nutshell, if you have more memory than you know what do to with, stick with ext3. If you spend all your time waiting for disk operations to complete, go with reiserfs. Dax Kelson Guru Labs _______________________________________________ Jfs-discussion mailing list [EMAIL PROTECTED] http://www-124.ibm.com/developerworks/oss/mailman/listinfo/jfs-discussion
