> I believe one of the reasons Sun3s get better serial port performance
> than Sparcs is because every time an interrupt for the port has to be
> handled, a Sun3 has to save 24 registers in the CPU, whereas the
> Sparc must save 192 registers.

(a) This depends on how many windows the particular machine has, no?

(b) Surely it doesn't spill every window, but rather just the full
     ones?  Perhaps it should just keep track of which full windows
     belong to the user and which to the kernel, and let the regular
     window overflow traps deal with saving user windows as necessary?
     If it really is dumping all windows on every interrupt, the
     performance benefit might be worth the code complexity....

					der Mouse

			    mouse@collatz.mcrcim.mcgill.edu