Re: register sets

On Sat, 19 Jul 2025 16:37:15 +0000, Anton Ertl wrote:

Robert Finch <robfi680@gmail.com> writes:

I am wondering if there is a way to tag each register individually with
the process id (app id) and involve the register renamer such that there
is no need to save / restore the register context.

>
Simulteneous multi-threading (SMT) tags each microinstruction and
instruction with a (hardware) thread id; two hardware threads may
belong to different processes.  How registers are handled probably
depends on the actual implementation, not sure if any implementation
tags it, but they all can tell which physical register belongs to
which hardware thread (if any).  And as long as you are not using more
hardware threads than your hardware has available, there is no need to
switch contexts, and therefore no need to save and restore it.

Correct, you tag the SMT instruction through the pipeline not the
registers in the files.
Also note:: SMT requires that the RM and FPflags be piped through
the FUs.

- anton