

Google at Carson’s Speed - ableal
http://www.cringely.com/2011/05/google-at-carsons-speed/

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ggchappell
Either I don't understand something, or else this article contradicts itself.

Apparently Google determined that they were spending more on electricity than
on silicon. And in their massively parallel world, 3 processors running at 1/3
speed are just as good as 1 running at full speed. So they buy more machines,
underpower them, and get the same results at lower cost.

As a result, Cringely claims, they have more computing power than they are
using, and they think about what to do with that extra power. But I reply:
they only have excess cycles if they switch back to running their servers at
higher power. And they've already decided not to do that. Thus, no excess
cycles, no unintended consequences, no "lead foot".

Right? Am I missing something? Is Cringely?

~~~
ableal
I posted this article because I found it thought-provoking, and I hadn't heard
of the Breguet Number and Carson’s Speed. But it does seem to me rather half-
baked (or even only one third ;-).

I was hoping that someone else would set the mess straight, including sorting
out the vague definitions, but no such lazyweb luck this time ...

First thing that looks wrong to me is that server power estimate at one-third.
I occasionally see CPU reviews with white-boxes benchmarking at something like
120W for idle power and 200W for full-throttle work, for CPUs rated at 90W or
so. Perhaps racked servers have less overhead, but I doubt they do any
significant work at 1/3 of full power. But I'd be happy to be contradicted by
someone with real info.

P.S. Coincidentally, in the LWN piece I also linked yesterday
(<http://news.ycombinator.com/item?id=2564007> ), commenters samth and incase
provided links to info about an IBM Research tool (Performance Analysis of
Idle Programs, by Erik Altman et al.). Web page:
[https://researcher.ibm.com/researcher/view_project.php?id=13...](https://researcher.ibm.com/researcher/view_project.php?id=1332)
. PDF paper: [https://researcher.ibm.com/researcher/files/us-
sjfink/res000...](https://researcher.ibm.com/researcher/files/us-
sjfink/res0000076-altman.pdf)

~~~
ggchappell
Well, it _was_ thought-provoking. And I also had never heard of the Breguet
Number & Carson's speed. So thanks for posting.

EDIT: Carson's speed is clearly a real concept. However, a web search turns up
nothing about the Breguet Number. Are we sure Cringely isn't just making this
up?

Also, FWIW, my original point (see GP by me) is also made in the comment by
NoTalentHack on Cringely's site.

