On 13 Apr 00, at 22:47, Francois LeBlanc wrote:
> On another note, I want to convince my University faculty (Science) to
> run Prime 95 in the computer labs. How can I prove that the client
> will not affect the performance of the computers; even the old Pentium
> 60ish. I'm not sure if I believe that myself.
On Windows machines, if you have the priority set to 1, then the
operating system will always run anything which is running at a
higher priority than 1 and actually needs CPU time, rather than
running Prime95. Normal applications run at 7, even screensavers run
at 4. In other words, the OS will only give CPU cycles to Prime95 if
there is nothing else in a position to use them.
There is a _small_ memory overhead - the memory used by Prime95 for
its work vectors can be significant on systems with very limited
memory. The good news here is that the memory overheads are
proportional to the exponent, so running double checks on current
assignments (around 5 million) needs only 4 or 5 megabytes. Better
still, trial factoring assignments use very little memory, well under
1 megabyte.
The network overheads are a few hundred bytes occasionally. Certainly
nothing to be concerned about.
Don't forget you can also use the "time of day" stuff (in prime.ini)
to make Prime95 get completely off the system at times when the
system is required to be 100% dedicated to user applications.
Basically what I'm saying is that, if you can run what the users want
on a system (no matter how slow it is or how ungenerous its memory),
running Prime95 in the background as well should make no perceivable
difference to the system so far as users are concerned. For instance,
I have Prime95 running double-checks on a P100 laptop with 24 MB
memory; this system is noticeably under-resourced for running e.g.
Netscape Communicator 4.7, but shutting down Prime95 doesn't make it
obviously less so.
There is one exception known to me. If the user is running a program
under the control of a software based debugger, then running Prime95
(or _any_ other background CPU soak program) can cause significant
performance degradation, not because of the resources used by Prime95
but because of all the extra task switches generated at each debugger
trap point - this can be as often as after every machine instruction
executed by the program being debugged.
> And at what speed do
> computers start being automatically assigned factoring assignments.
Used to be 50 MHz (based on CPU speed set in CPU/Options, multiplied
by 0.001 * RollingAverage (from local.ini), multiplied by hours per
day set in CPU/Options, divided by 24). But you can override the
automatic assignment type using the Test/PrimeNet menu.
> I've already spoken
> to a technician but he wasn't very collaborative, saying that all
> sorts of permissions were needed but I haven't given up yet.
Yes, you _do_ need permission, at the level of corporate beaurocracy.
But the network priveleges required are minimal, essentially
Prime95's communications with PrimeNet will work if the system can
see PrimeNet's home page with an ordinary web browser. Unlike some
projects, Prime95 does _not_ automatically change its program code
under control of the server, so running Prime95 does not present any
particular problems from the point of view of system security.
Unfortunately, tiny minds with power will always come up with
"technical" objections when what they really mean is "I can't be
bothered" 8-(
Regards
Brian Beesley
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