Apologies for the resend... On Thu, Apr 30, 2015 at 11:01 AM, Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote: > > > On Thu, Apr 30, 2015 at 10:37 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> > wrote: >> >> On Thu, Apr 30, 2015 at 10:34:02AM -0400, Chuck Lever wrote: >> > I?ve been discussing the possibility of adding more session slots on >> > the Linux NFS client with jlayton. We think it would be straightforward, >> > once the workqueue-based NFSD patches are in, to make the backchannel >> > service into a workqueue. Then it would be a simple matter to increase >> > the number of session slots. >> > >> > We haven?t discussed what would be needed on the server side of this >> > equation, but sounds like it has some deeper problems if it is not >> > obeying the session slot table limits advertised by the client. >> >> No, the client isn't obeying it's own slot limits >> >> The problem is when the client responds to a callback it still >> holds a references on rpc_rqst for a while. If the server >> sends the next callback fast enough to hit that race window the >> client incorrectly rejects it. Note that we never even get >> to the nfs code that check the slot id in this case, it's low-level >> sunrpc code that is the problem. > > > We can add dynamic allocation of a new slot as part of the backchannel reply > transmit workload. That way we close the race without opening for violation > of session limits. > > Cheers > Trond -- 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
