Messages in this thread | | | Subject | Re: which ioctls matter across filesystems | From | Trond Myklebust <> | Date | Fri, 29 Apr 2005 17:13:19 -0400 |
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fr den 29.04.2005 Klokka 16:47 (-0400) skreiv Robert Love: > On Fri, 2005-04-29 at 16:42 -0400, Trond Myklebust wrote: > > > The problem is that having the server call back a bunch of clients every > > time a file changes does not really scale too well. The current > > dnotify-like proposal therefore specifies that notification is not > > synchronous (i.e. there may be a delay of several seconds), and that the > > server may want to group several notifications into a single callback. > > Yah, so what I am asking is why not use inotify for the user-side > component of this system?
> Wouldn't the deferring and coalescing of events occur on the server > side? So the server-side stuff would be whatever you need--your own > code using whatever protocol you wanted--but the client-side interface > would be over inotify.
Sure. We're not talking about inventing new user interfaces here. Just how best to support the existing ones.
> Even if not, I'd be willing to make changes to inotify to accommodate > NFS's needs.
I think what the IETF NFS working group rather needs right now is an advocate that is willing to stand up and demonstrate why protocol support for inotify-style callbacks would be a more scalable solution than a solution based on a combination of GETATTR polling and read delegations (essentially the same thing as CIFS' op-locks) for directories.
The current research (see http://www3.ietf.org/proceedings/05mar/slides/nfsv4-4/sld1.htm) which has uses real-life on-the-wire traffic actually leans more towards the GETATTR solution. That research was based on a set of anonymous tcpdump traces taken at Harvard University, though, so it reflects the traffic in a typical university environment. It may be that other use-cases exist that favour the inotify callbacks case. If so, now is the time to step forward and say so...
Cheers, Trond -- Trond Myklebust <trond.myklebust@fys.uio.no>
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