On 01/22/2013 02:42 PM, Emmanuel Florac wrote: > Le Tue, 22 Jan 2013 13:50:59 +0100 > Samuel Kvasnica <samuel.kvasnica@xxxxxxxxx> écrivait: > >> Actually, funny way, noalign is always better that sw/su alignment for >> any hardware-RAID I tried so far. > It may be because of lvm in case you're using it. No, no LVM. And no partitions. The filesystem lives directly on raw device, even no partition table there. I have actually never seen this working (except on mdraid), but noalign gives perfect performance so I do not bother much. > >> But I do not think that mkfs or mount is that much relevant here as >> the local filesystem performance is pretty Ok (actually same as raw >> dd). >> >> The bottleneck issue comes only when exported by NFS over RDMA. And it >> seems more like a "pumping effect" >> that bottleneck. >> > NFS tends to make small IOs and can be tricky, in your case it reminds > me of a random access bottleneck, for instance log access. That's why > I'm wondering what iostat output looks like... Periodical log flushing > could be the culprit. But I read/write only long files in this test (100GB). The point is btrfs has not this issue and I do not remember seeing it earlier around 2.6.x kernels. There must be some IO-buffer issue. As I remember there used to be quite some NFS-specific code within the XFS tree. regards, Samuel _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
