TOP2 probably illegal smart moves

By: Jouni Osmala (josmala.delete@this.cc.hut.fi), September 29, 2009 11:08 pm
Room: Moderated Discussions
>>>I don't think that P6 really stole much from Alpha. The really tricky part for
>>>P6 was figuring out how you might get x86-->uops efficiently with sufficient ILP for OOOE.
>>
>>Yes. My impression was that it was Pentium (not PentiumPro)
>>that involved more, to put it politely, disputed technology.
>>The relative timing of the first Alpha AXP and the first
>>Pentium would suggest that was plausible. And since Intel
>>ended up paying about $700M to DEC (admittedly in a complex
>>deal which bought Intel a fab and various other stuff), I
>>tend to think there was some substance to DEC's claims.
>>
>>Pentium was the first time Intel went superscalar; and it
>>was the first time they got in the same ballpark as RISC
>>(at least the weaker RISCs - Pentium overtook SPARCstation,
>>and stayed ahead as it ramped up clockspeed while
>>SuperSPARC flopped). If you see a mediocre hitter who
>>suddenly starts hitting 40+ home runs, you reckon he's
>>probably cheating. And Intel's cpu designs made that kind
>>of leap between 486 and Pentium.
>>
>>
>
>The leap between 486 and Pentium had four main contributors:
>1. Writeback on-chip data cache (486 on-chip cache was write through and unified with instruction cache).
>2. Faster _and_ wider external bus - 4x peak throughput
>3. Pipelined FPU - about 10x peak theoretical throughput over i486 and more than twice lower latency
>4. 2-way superscalarity
>
>I don't know which of the first three factors was the most important but I am pretty
>sure that the fourth factor (superscalarity) was not nearly as significant as either of the first three.
>
>Do you remember what exactly, according to DEC's claim, Intel stole from them? Was it from Alpha or from VAX

If I recall correctly it was about branch predictor. Used in PPro.
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TopicPosted ByDate
TOP3 blundersanon2009/09/25 07:38 PM
  TOP3 blundersrwessel2009/09/25 07:58 PM
  TOP3 blundersPotatoswatter2009/09/26 02:12 AM
    TOP3 blundersJouni Osmala2009/09/26 08:47 AM
    TOP3 blundersWilco2009/09/26 10:51 AM
      TOP3 blundersPotatoswatter2009/09/26 01:04 PM
        TOP3 blundersRagingDragon2009/09/28 02:58 PM
  TOP3 blunders?2009/09/26 03:44 AM
    TOP3 blundersanon2009/09/26 06:55 AM
      TOP3 blunders?2009/09/26 10:49 AM
        TOP3 blundersPotatoswatter2009/09/26 01:38 PM
        TOP3 blundersJouni Osmala2009/09/26 09:52 PM
          TOP3 blunders?2009/09/27 01:08 AM
            implementationAM2009/09/27 01:31 AM
          the generic mechanismAM2009/09/27 01:15 AM
            the generic mechanism?2009/09/27 02:30 AM
          TOP3 blunderssomeone2009/09/27 07:49 AM
            TOP3 blunders?2009/09/27 08:33 AM
              TOP3 blundersBlistering blue barnacles2009/09/28 08:44 PM
              TOP3 blundersslacker2009/09/29 07:28 AM
                (12nJ/cycle)*3GHz = 36W (NT)Michael S2009/09/29 08:31 AM
                  That's what I get for posting so early. (NT)slacker2009/09/29 06:17 PM
          TOP3 blunderskoby m.2009/09/29 07:26 AM
            TOP3 blundersJouni Osmala2009/09/29 11:05 PM
              TOP3 blunders?2009/09/30 02:26 AM
    TOP3 blundersPotatoswatter2009/09/26 07:11 AM
      TOP3 blunderssomeone2009/09/26 09:26 AM
    ISA extensions - tensilica?David Kanter2009/09/26 10:17 AM
      ISA extensions - StretchWes Felter2009/09/26 11:24 AM
        ISA extensions - Stretch?2009/09/26 01:14 PM
          ISA extensions - StretchGabriele Svelto2009/09/28 03:14 AM
  TOP3 blundersanonymous2009/09/26 06:23 AM
  TOP3 smart movesanonib2009/09/26 07:11 PM
    TOP3 smart movesDavid W. Hess2009/09/26 07:55 PM
      TOP3 smart movesRichard Cownie2009/09/27 01:57 PM
        TOP3 smart movesRagingDragon2009/09/28 03:46 PM
    TOP3 smart movesa reader2009/09/27 08:44 AM
    TOP3 smart movesRichard Cownie2009/09/27 12:12 PM
      TOP2 probably illegal smart movesRichard Cownie2009/09/27 01:43 PM
        TOP2 probably illegal smart movesnn2009/09/27 07:27 PM
        TOP2 probably illegal smart movesDavid Kanter2009/09/29 01:48 AM
          TOP2 probably illegal smart movesRichard Cownie2009/09/29 10:31 AM
            TOP2 probably illegal smart movesMichael S2009/09/29 11:04 AM
              TOP2 probably illegal smart movesDavid Kanter2009/09/29 01:35 PM
              TOP2 probably illegal smart movesRichard Cownie2009/09/29 04:28 PM
              TOP2 probably illegal smart movesJouni Osmala2009/09/29 11:08 PM
              Link to good analysis on the matter.Jouni Osmala2009/09/29 11:22 PM
                Link to good analysis on the matter.Richard Cownie2009/09/30 09:59 AM
  TOP3 blunder of todayMichael S2009/09/29 04:31 AM
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