Subject: Re: CG6 and serial port support questions
To: None <port-sparc@NetBSD.ORG>
From: der Mouse <mouse@Collatz.McRCIM.McGill.EDU>
Date: 03/13/1996 06:44:34
> 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....