In addition to Dave's comments, consider the following from Val's article with Alex quoted: The overall performance result was that the Featherstitch implementations were at par or somewhat better with the comparable ext3 version for elapsed time, but used significantly more CPU time..... So, you can use Featherstitch to re-implement all kinds of file system consistency schemes - soft updates, copy-on-write, journaling of all flavors - and it will go about as fast the old version while using up more of your CPU. And note that this was comparing against ext3, which is not exactly a shining example of performance. (i.e., ext4 and xfs tend to beat ext3 handily on most benchmarks.) Furthermore, given the sort of dependency tracking which Featherstich is attempting, I suspect that the results will be at the very least interesting on a system with a large number of cores; it's very likely that it's CPU scalability leaves much to be desired. Finally, note that many disk drives do not perform all that well with writeback caching disabled (which is required for soft update and its variants). So when people do benchmarks comparing soft updates versus traditional file systems, and important question to ask is (1) did they remember to disable writeback caching for the soft updates run (which is not the default, and if you don't disable it, you lose your powerfail relibility), and (2) was writeback caching enabled or disabled when benchmarking the traditional system, which can safely use the default HDD writeback caching. Regards, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
