[r-t] Exhausted search spaces

Simon Humphrey sh at keystrata.co.uk
Fri Feb 5 10:04:48 UTC 2010

On Thu, 04 Feb 2010 23:04:37 +0000
Mark Davies <mark at snowtiger.net> wrote:

> Anyway, Simon H must have a pretty slow computer, because I've just
> run the same search for six minutes and I got 10.89 million
> compositions (not counting rotations).

Interesting. This machine has a 3.0GHz Pentium, with hyper-threading
disabled so as to allow SMC to use the whole 3.0 GHz despite being
single-threaded. The processor is fairly elderly and single-core,
Surely you don't have a 6 GHz processor, Mark? I thought 3.0 Ghz is
still about the limit for processor speed/  Modern technology is only
able to provide more computing power by squeezing multiple processors
onto the same chip, but that won't speed up single-threaded

Could I/O be the bottleneck on my machine? I didn't think so, since
(according to Task Manager) SMC was driving the processor at 100% all
the time, but perhaps a big chunk of the processor is being consumed by
disk write requests. Evidently Mark's machine was producing 30,000
compositions per second, which is just 33 microseconds per
composition, while mine was lumbering along at a dismal 66
microseconds.  If there's one write per composition that's still a
phenomenal I/O rate though.

I suspect my ancient motherboard and RAM may be limiting factors.  That
would give me an excuse to build a new machine with up-to-date
components :-)


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