Re: Pi program and hard disk usage

On Sep 22, 4:45 pm, mike3 <mike4...@xxxxxxxxx> wrote:
Hi.

I used the profiler that comes with Intel's C compilers, and it seems
the pi program, for large runs, is spending the great deal of time
accessing or waiting for the hard drive. In fact it was way down the
list of amount of CPU cycles used (with other programs at the top
spot).

There is no surprise here. Even at 15K RPM it takes 1/15000 of a
minute to make a rotation for a 15K RPM drive which is the fastest
commonly available.
So your program is going to wait on the disk, and it won't be
consuming CPU unless you thread it so that it can do something useful
while the platter is coming around. Even at that, you will be sorely
pushed to find somthing to do to fill all of that slack time.

Is there any way to make it use up a lot more of the system and
hence go faster?

Perform the calculations in RAM instead of on disk.

Thanks. You can see the source code at the links I've
provided in the previous threads on this subject.

I think Mr. Harter's (IIRC) suggestion is going to be pretty near to
optimal. You might improve it a bit with LRU cacheing or something,
but no matter what you do you will be waiting on the disk. I think
that also is plainly obvious.

.

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