On Wed, Aug 14, 2013 at 07:24:01PM -0700, Andi Kleen wrote: > > And FWIW, it's no secret that XFS has more per-operation overhead > > than ext4 through the write path when it comes to allocation, so > > it's no surprise that on a workload that is highly dependent on > > allocation overhead that ext4 is a bit faster.... > > This cannot explain a worse scaling curve though? The scaling curve is pretty much identical. The difference in performance will be the overhead of timestamp updates through the transaction subsystems of the filesystems. > w-i-s is all about scaling. Sure, but scaling *what*? It's spending all it's time in the filesystem through the .page_mkwrite path. It's not a page fault scaling test - it's a filesystem overwrite test that uses mmap. Indeed, I bet if you replace the mmap() with a write(fd, buf, 4096) loop, you'd get almost identical behaviour from the filesystems. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
