On Fri, 15 Mar 2013, Huang, Xiwei wrote: > ok. Thanks. Is there any documentation for ceph fs client arch as a > reference if I'd like to look into this? Not really. The code you are interested in is fs/ceph/file.c. The direct io path should be pretty clear; it'll build up a list of pages and pass it directly to the code in net/ceph/osd_client.c to go out over the wire. Enabling debugging (echo module ceph +p > /sys/kernel/debug/dynamic_debug/control, same for module libceph) and doing a single large direct-io write should show you where things are going wrong. sage > > ???? iPhone > > ? 2013-3-14?23:23?"Sage Weil" <sage@xxxxxxxxxxx> ??? > > > On Thu, 14 Mar 2013, Huang, Xiwei wrote: > >> Hi, all, > >> I noticed that CephFS fails to support Direct IO for blocks larger than 8MB, say: > >> sudo dd if=/dev/zero of=mnt/cephfs/foo bs=16M count=1 oflag=direct > >> dd: writing `mnt/cephfs/foo: Bad address > >> 1+0 records in > >> 0+0 records out > >> 0 bytes (0 B) copied, 0.213948 s, 0.0 kB/s > >> My version Ceph is 0.56.1. > >> ??I also found the bug has been already reported as Bug #2657. > >> Is this fixed in the new 0.58 version? > > > > I'm pretty sure this is a problem on the kernel client side of things, not > > the server side (which by default handles writes up to ~100MB or so). I > > suspect it isn't terribly difficult to fix, but hasn't been prioritized... > > > > sage > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
