Just thought I would send out a note outlining the state of the mips64 port. Ralf, Ulf and I have been actively working past few months to bring up Linux on the SGI ccNUMA machines.
The executive summary: we have achieved multiuser boot on o200 and o2000s. The largest configuration is a 32p, 16node machine (only approx 4G worth of memory was populated over the 16 nodes, the system can take 4G * 16 node worth of memory). This machine has 10 PCI busses, with 24 scsi controllers and 10 disks. (Sample output is at
If you are interested in the system architecture and details of the port, read on. The o2000s use R10000 series of MIPS processors. Each machine is comprised of modules, each module has 4 node boards with max 2 cpus and 4G memory on each node, and IO boards and routers. In a module, the two alternate node boards are each connected to a XBOW. Each XBOW possibly is connected on the other side to a number of PCI busses, which is what the IO boards connect to. Apart from this, there are routers in the system that provide connection paths between all memory to all cpus, to create a true CC-NUMA architecture.
On the software side, we are still struggling with compiler and binutils issues. The kernel itself is 64 bits, created by cross compiling on an ia32 box. We have not attempted 64 bit user program compilation or execution. The root disk is currently very close to the MIPS/Indy root disks. The architecture specific code uses the CONFIG_DISCONTIGMEM code to support memory on all nodes. The architecture specific NUMA features currently are: 1. replicate the kernel text on all nodes, so that no one node becomes a memory hot spot (unfortunately, the kernel data has to reside on only one node). 2. replicate low level excpetion handler code on all nodes. The architecture code also turns on CONFIG_NUMA to take advantage of node-local page allocations. (A CONFIG_NUMA patch that I have been submitting to Linus was put into the kernel in test6-pre1). For more information on NUMA and ongoing work, refer to
The purpose of doing this port is to boot Linux on bigger systems that we have, in order to do cpu/memory scalability studies. This also lets us do NUMA performance work in the future. Another advantage is to be able to leverage this work on the upcoming SGI CC-NUMA Itanium boxes, which will be an SGI supported product. Initial results from scalability studies using mips64 is documented at
The OSS SGI site.