macro-op vs. micro-op

Article: Inside Barcelona: AMD's Next Generation
By: dess (, May 22, 2007 3:56 am
Room: Moderated Discussions
David Kanter ( on 5/22/07 wrote:
>Unfortunately, I couldn't quite get macro-op, or micro-op to really fit well in
>the diagrams. We have a 750p wide constraint, and anything larger will cause clipping
>problems. Hence I prefer uop to micro-op, despite confusion potential. Perhaps I should update the article.

Taking a look on the mentioned documents, I feel it would be appropriate. Given the micro-ops cannot be fused on AMD's, but an AMD-termed macro-op can contain two micro-ops, it's somewhat prejudical on the side of AMD's to use micro-op in place of (their) macro-op.

>>>However, Intel is a different story. First of all, the >term is uop, not micro-op,
>>You used "uop" also on Barcelona's diagrams.
>See above comments.

How you feel about using "mop" on Barcelona's? Alternatively, you could use the number of actual micro-ops, so f.ex. "3-6 uops" in case of 3 macro-ops, etc.

>>Taking into account that AMD's 3 decoders are responsible >of decoding 95% of the
>>instruction set/modes
>According to whom, and on what workload?

Software Opt. Guide for AMD Family 10h Processors, Appendix C, Instruction Latencies, where all the instructions are listed, with a field of Decode Type, so that whether it is either DirectPath, DirectPath Double, or VectorPath. Taking only general purpose and integer instructions, the ratio is like 60%/40%, or so. (I have no statistics on the usage ratio on them in actual core, but I would think compilers and asm programmers prefer the DirectPath, or DirectParh Double ones, if possible.) Along the multimedia instructions, it's more like 90/10.

>>(the uCode Engine works with the >remaining 5%,
>Again, which workload?

(See the above comment.)

>It seems to me that you probably don't have data on the % of operations that decode to 1,2,3,4+ uops.

Right, I have no exact data on this, on Intel CPUs, I just rely on some comments here and there.

>>Moreover, AFAIK, AMD's Pack Buffer emits 3 _macro-ops_, >whose can contain up to
>>6 micro-ops, while Intel's path is 4 _uop_. Or is this >"uop" a macro-op in AMD's terms?
>Intel's uops and AMD's micro-ops, macro-ops, etc. are not really comparable directly.

Right, but I would take here what Agner wrote about it: "A macro-operation in AMD terminology is somewhat similar to a fused micro-operation in Intel terminology." (BTW, Agner is using micro-op all along, also on Intel's CPUs, instead of uop. uop is perhaps just a witty abbrevation, isn't it?)
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TopicPosted ByDate
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    Yes, I left out a sentence there. Fixed (NT)David Kanter2007/05/16 12:07 PM
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  microops vs macroops on page 4Peter Lund2007/05/17 12:04 PM
    microops vs macroops on page 4David Kanter2007/05/21 04:51 PM
      microops vs macroops on page 4EduardoS2007/05/21 05:42 PM
        microops vs macroops on page 4dess2007/05/21 07:00 PM
  Barcelona Article OnlinePeter Lund2007/05/17 12:25 PM
  macro-op vs. micro-opdess2007/05/21 07:24 AM
    macro-op vs. micro-opDavid Kanter2007/05/21 04:38 PM
      macro-op vs. micro-opdess2007/05/21 06:15 PM
        macro-op vs. micro-opDavid Kanter2007/05/22 12:11 AM
          macro-op vs. micro-opdess2007/05/22 03:56 AM
            macro-op vs. micro-opGipsel2007/05/22 05:05 AM
              macro-op vs. micro-opdess2007/05/22 05:52 AM
                macro-op vs. micro-opanonymous2007/05/22 06:14 AM
                  macro-op vs. micro-opdess2007/05/22 06:44 AM
                    macro-op vs. micro-opEduardoS2007/05/22 02:19 PM
                      macro-op vs. micro-opdess2007/05/24 08:52 AM
            Stop comparing apples to orangesEduardoS2007/05/22 02:30 PM
              Stop comparing apples to orangesdess2007/05/22 04:09 PM
                Stop comparing apples to orangesdess2007/05/22 04:30 PM
                Stop comparing apples to orangesEduardoS2007/05/22 04:31 PM
                  Stop comparing... apples to oranges?dess2007/05/24 09:30 AM
              Stop comparing apples to orangesanonymous2007/05/22 08:12 PM
                Stop comparing apples to orangesEduardoS2007/05/23 02:50 PM
          macro-op vs. micro-opanonymous2007/05/22 06:08 AM
            macro-op vs. micro-opdess2007/05/22 06:40 AM
              macro-op vs. micro-opanonymous2007/05/22 06:48 AM
      macro-op vs. micro-opdess2007/05/21 08:30 PM
        macro-op vs. micro-opanonymous2007/05/22 06:44 AM
          macro-op vs. micro-opdess2007/05/24 09:38 AM
      macro-op vs. micro-opMichael S2007/05/22 05:26 AM
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