On Sat, Oct 04, 2008 at 09:34:49PM +0800, Roy M. wrote: > Hello, > > On Sat, Oct 4, 2008 at 5:52 AM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: > > I doubt the pattern of I/O really matters much--it's the opens and > > closes themselves that matter. > > > > (In v3, close-to-open cache consistency requires that the client always > > fetch file attributes from the server on an open. That means open() is > > always going to take at least the ping time to the server. In v4 in > > some situations the client can do the open with no call to the server at > > all--by comparison such an open is almost instantaneous. If you're > > doing a ton of opens all in a row, that may make a difference.) > > > > In existing v3, you mean even if a file is cached locally by client, > in each open, the file attributes need to be read from NFS server > everytime? Right. The client has to do that to check whether someone else has changed the file. See http://nfs.sourceforge.net/#faq_a8 for an explanation of close-to-open cache consistency, which is what requires this. > But I just wonder without reading the NFS server, how the consistency > was maintained... I'm afraid I don't understand the question. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
