On Wed, 2011-04-13 at 10:02 -0400, Jeff Layton wrote: > We could put the rpc_rqst's into a slabcache, and give each rpc_xprt a > mempool with a minimum number of slots. Have them all be allocated with > GFP_NOWAIT. If it gets a NULL pointer back, then the task can sleep on > the waitqueue like it does today. Then, the clients can allocate > rpc_rqst's as they need as long as memory holds out for it. > > We have the reserve_xprt stuff to handle congestion control anyway so I > don't really see the value in the artificial limits that the slot table > provides. > > Maybe I should hack up a patchset for this... This issue has come up several times recently. My preference would be to tie the availability of slots to the TCP window size, and basically say that if the SOCK_ASYNC_NOSPACE flag is set on the socket, then we hold off allocating more slots until we get a ->write_space() callback which clears that flag. For the RDMA case, we can continue to use the current system of a fixed number of preallocated slots. Cheers Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- 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
