3 ms·

Curious, would OoO execution been possible with CMS? It's complicated enough to resolve things when you're dealing with instructions + hardware execution units

by ethbro 6y ago

Curious, would OoO execution been possible with CMS? It's complicated enough to resolve things when you're dealing with instructions + hardware execution units. When that becomes x86 instructions + CMS + native instructions + hardware execution units... it seems a daunting task to hit stability and outlier response targets for the system as a whole.

FullyFunctional 6y ago
The whole thing was already incredibly complex: getting the x86 semantics and state right, generating perfectly scheduled P95 code that had the the most useful speculation - while avoiding known hazards in the hardware, etc. Using a speculative superscalar OoO would migrate part of the complexity from software to hardware. The major concern cited is usually power, but I don't know how much the renamer + scheduler would add relative to everything else; the hardware already had all the rest: extensive speculation support, branch predictors, large register file, store buffers, etc. It's a fascinating topic and this isn't the ideal forum. However my point is this: there are very few companies out that that tries something truly new, and when one does and fail in the market there too much "told you so" going around.
- ethbro 6y ago
  > However my point is this: there are very few companies out that that tries something truly new, and when one does and fail in the market there too much "told you so" going around. Absolutely agreed. And from what I hear, the spirit of Transmeta ended up in a lot of other places (either via cleanroom design of similar tech, personnel working on similar projects, or inspiration). People are also starting to wake up to the just how underhanded and illegal technology companies will behave to squash their competitors, whereas I think the 00s still had rose tinted glasses about the best technical product winning.
FullyFunctional 6y ago
This is a little late, but this link is relevant: http://datasheets.chipdb.org/Transmeta/pdfs/Transmeta_Efficeon_Launch.pdf http://datasheets.chipdb.org/Transmeta/pdfs/Transmeta_Effice... I had forgotten just how short the pipe was (~ 7 stages!). Going OOO would have added at least one stage.

by ethbro 6y ago

FullyFunctional 6y ago

The whole thing was already incredibly complex: getting the x86 semantics and state right, generating perfectly scheduled P95 code that had the the most useful speculation - while avoiding known hazards in the hardware, etc. Using a speculative superscalar OoO would migrate part of the complexity from software to hardware. The major concern cited is usually power, but I don't know how much the renamer + scheduler would add relative to everything else; the hardware already had all the rest: extensive speculation support, branch predictors, large register file, store buffers, etc. It's a fascinating topic and this isn't the ideal forum. However my point is this: there are very few companies out that that tries something truly new, and when one does and fail in the market there too much "told you so" going around.

ethbro 6y ago
> However my point is this: there are very few companies out that that tries something truly new, and when one does and fail in the market there too much "told you so" going around. Absolutely agreed. And from what I hear, the spirit of Transmeta ended up in a lot of other places (either via cleanroom design of similar tech, personnel working on similar projects, or inspiration). People are also starting to wake up to the just how underhanded and illegal technology companies will behave to squash their competitors, whereas I think the 00s still had rose tinted glasses about the best technical product winning.

FullyFunctional 6y ago

This is a little late, but this link is relevant: http://datasheets.chipdb.org/Transmeta/pdfs/Transmeta_Efficeon_Launch.pdf http://datasheets.chipdb.org/Transmeta/pdfs/Transmeta_Effice... I had forgotten just how short the pipe was (~ 7 stages!). Going OOO would have added at least one stage.