On Tue, Oct 9, 2012 at 11:32 AM, Sam Lang <sam.lang@xxxxxxxxxxx> wrote: > Putting a delay on the sender would avoid the reordering of messages that > have semantic meaning but allow delay-caused reordering to occur for those > that have no semantic dependency. > > You're right that reordering at the receiver won't work, but it would be > nice to have more concrete examples. The only example I can come up with is > the unsafe/safe messages from mds to client. Even in that case it looks > like we handle it by throwing away the unsafe message. What other examples > exist? Caps issue/revoke? in the OSDs then requests to the same object are all strictly ordered, and responses need to be ordered in the same way — everybody through the whole chain asserts out if that's not the case. I haven't thought it through on the MDS, but yeah, caps messages on the same inode (or inodes in a hierarchical relationship) all need to be ordered. Most of the rest of its messages I can come up with aren't going to have semantic meanings without the client already waiting, so it's got fewer problems than the OSDs do. -- 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
