[Pc_Support] AMD's L1 cache is 4x larger than Intel's L1 cache -- WAS: HP dv2500nr

[Bryan J. Smith]

On Fri, 2006-07-21 at 10:41 -0400, Kyle Gonzales wrote:
> I will not buy a Turion X2 chip.  256k L2 per core?

First off, since when does L2 cache have _anything_ to do with
performance?  If that was the case, then Intel's 2-4MB L2 cache on the
P4 processors should have been be smacking the A64 silly!

Secondly, people _forget_ that AMD processors have *4*TIMES* the L1
cache of Intel processors!  L1 is far, far more of a consideration --
especially in how AMD's non-exclusive cache design works compared to
Intel's exclusive cache design.

I.e., In an Intel processor, it _must_ load data into L1 cache before
the registers.  In an AMD processor, it can _directly_ load from L2
cache into registers.  With a _small_ L1 cache, the Intel really hurts
from this.

People forget about AMD's L1 cache _advantage_.  It's a major reason why
AMD is able to "keep up" with Intel's fabrication lead.  In fact, Intel
often has to "waste transistors" in adding more L2 to "make up" for its
small L1.

> Blah, its already testing out poorly.

No, not "poorly."  AMD HyperTransport (A64/T64) processors do _smack_
Intel NetBurst (P4) processors silly.

> I'll wait for the Core 2 Duo for the laptop.

Now Core 2 Duo _is_ different.  Intel has finally _chucked_ 




> My wife has a Turion chip in her laptop, and it runs well.  However, the
> cache (or lack thereof) on the Turion X2 is a dealbreaker for me.

Huh?  Why does the L2 cache matter?

For _me_, the L1 cache size in Intel's processors and the requirement
that _all_ L2 go through that _tiny_ L1 is the "deal breaker."  ;->

Seriously now, buying something for L2 cache size is like saying you're
not going to buy a car with a smaller gas tank.  Yeah, it can't feed the
engine and go as far without stopping for gas than a car with a bigger
gas tank.

But the L2 cache has _nothing_ to do with the L1 cache like the gas tank
has _nothing_ to do with the displacement of the engine.  Seriously!
Yeah, my car with a smaller gas tank will "stall" before the larger one
unless I get gas -- but with 4x the engine displacement like L1 cache, I
_could_ be much farther down the road when I do stop!  ;->

Com'mon Kyle!  You've been listening to marketing.  ;->

Buy a Core 2 Duo because of the _performance_.  The L2 cache has
_nothing_ to do with that.  There's no more proof in that than the
massive and often _useless_ L2 cache sizes of the Netburst (P4)
architecture.  You could put 32MB of L2 cache on a Netburst and it
_still_ would _not_ beat an AMD A64-based design.

Again, the Core 2 Duo is a return to and an improvement over the
original P6 (Pentium Pro) core.  That's why it's very, very competitive
with AMD MHz for MHz -- _unlike_ Intel Netburst (P4).  And because Intel
has a 12-18 month lead in fabrication over AMD (because fabs cost
_billions_ of dollars), Intel can offer higher frequencies for the same
series/price.

Hence why Core 2 Duo wins.  It has _little_ to do with L2 cache size,
especially given AMD's _superior_ L1 cache feed directly to the
registers.

-- 
Bryan J. Smith          Professional, technical annoyance
mailto:b.j.smith at ieee.org    http://thebs413.blogspot.com
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