On Fri, Jun 29, 2012 at 12:25:06PM +0100, Mel Gorman wrote: > Configuration: global-dhp__io-metadata-xfs > Benchmarks: dbench3, fsmark-single, fsmark-threaded > > Summary > ======= > Most of the figures look good and in general there has been consistent good > performance from XFS. However, fsmark-single is showing a severe performance > dip in a few cases somewhere between 3.1 and 3.4. fs-mark running a single > thread took a particularly bad dive in 3.4 for two machines that is worth > examining closer. That will be caused by the fact we changed all the metadata updates to be logged, which means a transaction every time .dirty_inode is called. This should mostly go away when XFS is converted to use .update_time rather than .dirty_inode to only issue transactions when the VFS updates the atime rather than every .dirty_inode call... > Unfortunately it is harder to easy conclusions as the > gains/losses are not consistent between machines which may be related to > the available number of CPU threads. It increases the CPU overhead (dirty_inode can be called up to 4 times per write(2) call, IIRC), so with limited numbers of threads/limited CPU power it will result in lower performance. Where you have lots of CPU power, there will be little difference in performance... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>