What you're thinking of is different from task/processor/thread affinity.
Regarding SGI, I'm guessing you're thinking about the Onyx, which would have put it about 1993+. The R4x00s that were in the machine were not powerful enough to drive the RE2 and IR boards on a shared basis. The scheduler on many of these machines (Ultrix and IRIX both, along with Unicos, etc.) all pretty much sucked at the time, with AIX being a notable exception in some environments, especially running under VM.
You still see dedicated task processors with the z-series and maybe i as well today.
What you're thinking of is different from task/processor/thread affinity.
Regarding SGI, I'm guessing you're thinking about the Onyx, which would have put it about 1993+. The R4x00s that were in the machine were not powerful enough to drive the RE2 and IR boards on a shared basis. The scheduler on many of these machines (Ultrix and IRIX both, along with Unicos, etc.) all pretty much sucked at the time, with AIX being a notable exception in some environments, especially running under VM.
You still see dedicated task processors with the z-series and maybe i as well today.