[Tfug] CPU Query

[Jim Secan]

> I assume you mean to imply that your tasks
> are "compute-bound" and not I/O-bound?  Do you
> have enough awareness of what the actual algorithms
> entail (e.g., fixed point vs. floating point, etc.)
>
> --don

I wrote all the code, so I know exactly what it's doing (OK, so I didn't
write the SVD package, but that's from one of the optimized libraries). 
I/O has all been optimized such that so you read it all in (binary
unformatted), crunch numbers, and then write it all out.  The "bind" is in
floating-point operations (mostly matrix manipulations - this is a largish
inverse problem).  My interest is in whether the OS can take advantage of
the 2X CPUs without my having to get a compiler (Fortran) that will do
this.  Either that, or get into the manual "loop unrolling" business,
which loses me more (in my time) than I would gain.  I want to know if
paying a little more for a 2X CPU will gain me in throughput without my
having to do anything other than copy codes over from my current FC3
system and go.  As a related side issue, I could care less about video
performance - I work at the command line and could live with this on a TTY
user interface.

I have heard that some OS's (distros) will do a sort of load-leveling, but
I don't know what sort of gain this would provide for a single process.  I
have doubts about that, and that's why I'm asking.  I certainly don't want
to find that I pay more for a 2X only to find that my processing runs
slower than a comparable speed (and cheaper) 1X because I gain nothing
from the second processor and lose from extra things the OS is doing
because it knows it has more than one processing path through the CPU.  I
have seen this sort of thing happen to people trying to parallelize or
vectorize their codes.  Definitely a YMMV situation (and possible also a
TANSTAAFL situation RE gain without pain).

Thanks.
Jim