On May 1, 2015, at 1:23 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Thu, Apr 30, 2015 at 01:41:02PM -0400, Chuck Lever wrote: >> We discussed this briefly during the Linux NFS town hall meeting. >> I agree using dynamic slot allocation for TCP is fine, and RPC/RDMA >> can use simple overprovisioning. >> >> This way the upper layer (NFSv4.1 client) doesn?t have to be aware of >> limitations in the RPC layer mechanism. >> >> Trond may have an additional concern that I didn?t capture. > > The other option would be to simply overallocate in the transport layer, > as that is the layer which causes the problem to start with. That’s exactly what the RDMA backchannel will do. > That being said, what is the argument for doing any sort of static > allocation here? I'm fine with doing fully dynamic allocation if that > works out fine, but a mixed static / dynamic allocation sounds like a > nightmare. RDMA resources must be allocated and pre-registered up front. The RDMA transport can’t support dynamic slot allocation without adding a lot more complexity. The RDMA transport will need to have separate backchannel setup and destroy methods anyway. So doing dynamic for TCP and overprovision for RDMA will be simple. -- Chuck Lever chuck[dot]lever[at]oracle[dot]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
