Tilera makes some really cool multicore CPUs. They have some PCI Express development boards that works nicely under Linux, so it definitely needed a Doom port. The ports are based on SDL Doom 1.10 which can be found here.
You can run 1 Doom process per core, up to a max of 30. More is of course possible, but I ran out of screen real estate. You can select which session to control, see the host code for details. There are some hacks provided for multi-keyboard input, but we never got that to work properly.
The Cisco SX80 uses a Tilera TILE-Gx36 CPU. Can it do something useful, like running Doom? Yes, of course!
MultiDoom for TILE-Gx source code (7 May 2014)
The TMC based version runs everything off the same clock so controlling more than 1 in parallel gives better results. There's a bug in the keyboard control code related to the way keys are transmitted. I probably won't bother fixing it since I don't have a TILE-Gx card anymore. If you fix it, please mail me a diff.
SDL MultiDoom for TILE-Gx PCIe TMC (6 August 2013)
The original iLib based port for the classic TILE64 chip. Newer versions of the devkit should have TMC available, so I recommend trying that instead.
SDL MultiDoom for TILE64 PCIe iLib (30 December 2009)