[HECnet] DECnet for Linux

To come back to the connection to MIM described below, it seems to be related to an unnecessary congestion issue. When connecting to a node, a configuration message contains the remote buffer size. MIM/RSX returns 2086.

Accordingly, dnprogs' libdap/connection.cc:set_socket_buffer_size sets setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &blocksize, sizeof(blocksize)) and likewise for SO_SNDBUF, as per protocol. But this triggers "on/off" flow control in the kernel module; the overhead to have a packet in the decnet socket buffers is such that the above blocksize is too small, even when it is doubled by default by the kernel - especially with the low value of 2086. Increasing it with (in exchange_config()) set_blocksize(min(MAX_READ_SIZE, cm->get_bufsize()<<1)); (or perhaps just set_blocksize(MAX_READ_SIZE); ?) helps a lot. Note that the kernel module and VMS announce "no flow control" (apart from "on/off"), and RSX uses "Session Control Message" flow control, which the kernel module implements for outbound data, so having the buffers perhaps too large may not be too problematic. PS: For creating a decnet.conf the 'dncopynodes' utility may be used.

On Wed, Jan 03, 2018 at 04:02:19PM +0100, Erik Olofsen wrote: > On a virtual machine with lubuntu 12.04, kernel 3.2.0, I have > DECnet for Linux V.2.5.68s working, with dnprogs version 2.65. > It is node RULLFL. > > The daemons and utilities use decnet.conf with node information, > so something useful would be to create it from mim::nodenames.dat. > > On a VAX, TYPEing it works well, but on the Linux machine, dntype > hangs after giving parts of the file; dndir mim:: works well. > > Does anyone have dntype mim::nodenames.dat working properly (with > perhaps different versions of the above)? > > Thanks! >