Re: Functional Local Static Zero Initialization - When?

From:
=?ISO-8859-1?Q?Marcel_M=FCller?= <news.5.maazl@spamgourmet.com>
Newsgroups:
comp.programming.threads,comp.lang.c++
Date:
Sun, 07 Dec 2008 11:33:35 +0100
Message-ID:
<493ba6cf$0$31879$9b4e6d93@newsspool3.arcor-online.net>
James Kanze schrieb:

On Dec 6, 1:44 pm, Marcel M?ller <news.5.ma...@spamgourmet.com> wrote:

you are right. The coherent caches of Intel CPUs do their Job.
I am still unsure whether this was a good idea with respect to
scalability.


There's a lot more that just cache coherency involved. The cost
of the Intel guarantees is negligible as long as all of the
cores are on a single chip. It's very, very costly if they
aren't.


I know. Syncronization over distance is costly.

Einsteins theory of relativity sets the limit in the way that events,
that are farther in space than in time compared to the speed of light,
are not related in any way. For bidirectional synchronisation it is only
half of the distance.

So within an 1GHz clock cycle you can synchronize at most over a
distance of 15 cm. Taking into account the reduced velocity of
propagation in condutors, the fact that the connection is not straight
and that electronic components are part of the game, you can certainly
reduce this distance to about 5cm.

Marcel

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