On Mon, Apr 23, 2018 at 09:03:26PM +0100, Nix wrote: > The XFS FAQ claims that this is, ah, not good for xfs performance, but > this may be one of those XFS canards that is wildly out of date, like > almost all the online tuning hints telling you to do something on the > mkfs.xfs line, most of which actually make performance *worse*. > > xfs folks, could you confirm that the deadline scheduler really is still > necessary for XFS atop md, and that CFS is still a distinctly bad idea? Yes, the problem still exists. CFQ just doesn't work well with workloads that issue concurrent, dependent IOs from multiple processes, nor does it work well with hardware raid arrays with non-volatile caches that have unpredictable IO performance. This sort of workload and hardware is common in the sorts of high performance applications we see run on XFS filesystems, and we avoid CFQ as much as possible.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
