Re: OoO execution

On Wed, 16 Jul 2025 14:27:11 +0000, John Savard wrote:

On Mon, 19 May 2025 22:04:22 +0200, Terje Mathisen wrote:

quadibloc wrote:

>

The Pentium II (and Pentium Pro) also only used OoO for floating-point,
while the 68050 only used OoO for integers!

>
Huh???
>
The Pentium (all versions) had two pipes (u & v), both in-order, and
with severe limitations on which opcodes could run in v in parallel with
the primary opcode in the u pipe.
>
The P6/PentiumPro OTOH does true OoO for all instruction types.
>
John, you are usually much better informed!

>
I had read somewhere that the Pentium Pro and the Pentium II, like the
System/360 Model 91, were OoO only in their floating-point pipelines. If
that source was faulty, and better sources say differently, I'll need to
check on it.

The Anderson papers indicate the /91 was just heavily pipelined in
the integer side.
I don't know about PPro in the integer section, but it was definitely
OoO in branches, the memory section, and in the PFU. So, I don't see
why they would not have had integer OoO.

>
John Savard