CPU @ 100%

acerdeville · 2011-06-18, 15:26

Just installed GIMP, and as soon as I started the program, my cpu maxed out. I restarted, and it maxed out again. Opened my process manager, and GIMP was using between 49-96%. I understood that it would not affect my performance very much, however with the CPU maxed, I can't do much. I closed the program, and my CPU dropped down to about 10%.
So what do I need to do?

xilman · 2011-06-18, 16:18

Quote:

Originally Posted by acerdeville

Just installed GIMP, and as soon as I started the program, my cpu maxed out. I restarted, and it maxed out again. Opened my process manager, and GIMP was using between 49-96%. I understood that it would not affect my performance very much, however with the CPU maxed, I can't do much. I closed the program, and my CPU dropped down to about 10%.
So what do I need to do?

You don't need to do anything and the behaviour you observe is normal. The program is designed to use all available CPU cycles at very low priority, which means it grabs the CPU only when nothing else wants it and gets out of the way the instant anything else wants to do something.

My machines spend virtually their entire life running at 100% CPU and yet hardly ever does it impinge on interactive work.

Paul

Uncwilly · 2011-06-18, 17:16

Yes, this is normal and it is fine.

The Prime95 program only fills in the gaps when nothing else is running. As you saw, when it is not running typically between 90-95% of the CPU time is wasted, Prime95 only takes that time.

As you noted, you saw 49%-96%. The first was likely while Prime95 had started a thread on 1 core and was waiting to start it on another.

And since Paul neglected to say it, "Welcome to the world of Prime Crunching".

acerdeville · 2011-06-18, 17:26

Thanks guys, I just misread the info. At this rate I'll find a prime in no time.

cheesehead · 2011-06-20, 01:24

Quote:

Originally Posted by acerdeville

however with the CPU maxed, I can't do much.

I think that if you'd actually tried doing something (word processing, browsing, whatever...), instead of only looking at the CPU-busy meter, you would have found that you could actually do whatever you wanted to do.

Christenson · 2011-06-20, 02:45

Quote:

Originally Posted by acerdeville

Thanks guys, I just misread the info. At this rate I'll find a prime in no time.

More likely you will find a non-prime in no time...the collective prime-crunchers have been looking for Mersenne Prime #48 (which may or may not be the 48th Mersenne Prime) for a couple years now...but nonetheless, good luck!

Mr. P-1 · 2011-06-20, 08:11

Quote:

Originally Posted by Christenson

More likely you will find a non-prime in no time...the collective prime-crunchers have been looking for Mersenne Prime #48 (which may or may not be the 48th Mersenne Prime) for a couple years now...but nonetheless, good luck!

His chances of finding a prime are quite good: most found factors are prime.

LiquidNitrogen · 2011-07-02, 19:58

Quote:

Originally Posted by Mr. P-1

His chances of finding a prime are quite good: most found factors are prime.

LOL!

Very funny, and equally true.

I think the OP meant "Mersenne Prime" though.

If you look at the total GHz-days reported on the Mersenne.org page, and divide that by 13 (the number of them found by GIMPS) that's the average GHz-days per prime.

Put your own GHz-days in the numerator, and that number in the denominator, and that is roughly your odds of finding a Mersenne.

Brian-E · 2011-07-02, 21:23

Quote:

Originally Posted by LiquidNitrogen

If you look at the total GHz-days reported on the Mersenne.org page, and divide that by 13 (the number of them found by GIMPS) that's the average GHz-days per prime.

Put your own GHz-days in the numerator, and that number in the denominator, and that is roughly your odds of finding a Mersenne.

Hmm, that will be very very roughly.

A sizeable proportion of that total GHz-days will be factoring work-types which would not in themselves discover a Mersenne Prime, or double checking which would be extremely unlikely to (never has so far). So obviously your work-type is very important: it needs to be LL and highly preferably first-time testing.
And the LL-work which is being done now is on much larger numbers than in the early days of GIMPS, and these numbers require far more GHz-days to test, plus it's also reasonable to assume that the Mersenne Primes will be more sparsely distributed in this current working zone: so the LL-work now will discover far fewer primes relative to GHz-days than the early work did.

LiquidNitrogen · 2011-07-03, 00:11

Quote:

Originally Posted by Brian-E

Hmm, that will be very very roughly.

A sizeable proportion of that total GHz-days will be factoring work-types which would not in themselves discover a Mersenne Prime, or double checking which would be extremely unlikely to (never has so far). So obviously your work-type is very important: it needs to be LL and highly preferably first-time testing.
And the LL-work which is being done now is on much larger numbers than in the early days of GIMPS, and these numbers require far more GHz-days to test, plus it's also reasonable to assume that the Mersenne Primes will be more sparsely distributed in this current working zone: so the LL-work now will discover far fewer primes relative to GHz-days than the early work did.

So I have 3 cores ddoing LL and 1 core doing D, so that means only the 3 cores are searching for Mersenne primes?

Christenson · 2011-07-03, 02:40

Yep, core #4 is, however, doing something important: Making sure that the first LL test indeed correctly reported that the exponent was a composite. There's a slight (probably worse than 1 in a million) chance that an exponent was incorrectly reported as composite -- it both has to be prime, and the first LL test has to have incorrectly reported it was composite.
P-1 is also good work for a CPU; I'm finding factors on average in significantly fewer GHz days than it would take to do two LL tests. You just have to give it a lot (a Gigabyte or so) of memory.

2011-06-18, 15:26	#1
acerdeville Jun 2011 10₂ Posts	CPU @ 100% Just installed GIMP, and as soon as I started the program, my cpu maxed out. I restarted, and it maxed out again. Opened my process manager, and GIMP was using between 49-96%. I understood that it would not affect my performance very much, however with the CPU maxed, I can't do much. I closed the program, and my CPU dropped down to about 10%. So what do I need to do?

2011-06-18, 17:16	#3
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 2²·23·107 Posts	Yes, this is normal and it is fine. The Prime95 program only fills in the gaps when nothing else is running. As you saw, when it is not running typically between 90-95% of the CPU time is wasted, Prime95 only takes that time. As you noted, you saw 49%-96%. The first was likely while Prime95 had started a thread on 1 core and was waiting to start it on another. And since Paul neglected to say it, "Welcome to the world of Prime Crunching".

2011-06-18, 17:26	#4
acerdeville Jun 2011 2₁₀ Posts	Thanks guys, I just misread the info. At this rate I'll find a prime in no time.

2011-07-03, 02:40	#11
Christenson Dec 2010 Monticello 5·359 Posts	Yep, core #4 is, however, doing something important: Making sure that the first LL test indeed correctly reported that the exponent was a composite. There's a slight (probably worse than 1 in a million) chance that an exponent was incorrectly reported as composite -- it both has to be prime, and the first LL test has to have incorrectly reported it was composite. P-1 is also good work for a CPU; I'm finding factors on average in significantly fewer GHz days than it would take to do two LL tests. You just have to give it a lot (a Gigabyte or so) of memory.