By: David W. Hess (dwhess.delete@this.banishedsouls.org), July 10, 2006 3:21 pm
Room: Moderated Discussions
Tzvetan Mikov (tmikov@gmail.com) on 7/10/06 wrote:
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>The table on page 2 is very interesting for me. The Pentium Pro had fewer transistors
>than the 21164, slower clock rate and yet it had a competitive specfp and higher specint (!!).
>
>What is the accepted explanation for this ? I figure it is the OoO which obviously favors integer code.
>
>However: Why did a OoO implementation of the x86 ISA need fewer transistors than
>an in-order implementation of Alpha ? Am I misreading the numbers (e.g. most of
>the transistors in teh Alpha could have been in the L3 cache, etc) ?
The listed 5.5 million transistors and 192mm2 die size for the Pentium Pro does not count the level 2 cache which was off chip but in the same ceramic package. The 256KByte cache was a custom 15.5 million transistor 202mm2 chip.
http://www.geek.com/procspec/intel/pentiump.htm
http://images.google.com/images?q=pentium%20pro
I will leave it to someone who knows more to estimate how many transistors and how much area Alpha's 96KByte level 2 cache used. The Alpha level 3 cache was off chip presumably using commodity high performance SRAM.
---------------------------
>The table on page 2 is very interesting for me. The Pentium Pro had fewer transistors
>than the 21164, slower clock rate and yet it had a competitive specfp and higher specint (!!).
>
>What is the accepted explanation for this ? I figure it is the OoO which obviously favors integer code.
>
>However: Why did a OoO implementation of the x86 ISA need fewer transistors than
>an in-order implementation of Alpha ? Am I misreading the numbers (e.g. most of
>the transistors in teh Alpha could have been in the L3 cache, etc) ?
The listed 5.5 million transistors and 192mm2 die size for the Pentium Pro does not count the level 2 cache which was off chip but in the same ceramic package. The 256KByte cache was a custom 15.5 million transistor 202mm2 chip.
http://www.geek.com/procspec/intel/pentiump.htm
http://images.google.com/images?q=pentium%20pro
I will leave it to someone who knows more to estimate how many transistors and how much area Alpha's 96KByte level 2 cache used. The Alpha level 3 cache was off chip presumably using commodity high performance SRAM.