Why factoring is single-core designed?

otutusaus · 2010-11-17, 15:58

Whenever I run factoring it's limited to "one core job", even if I assign more.
For example, setting up factoring on a Core2 Duo (1 worker/2 threads), it uses both cores but amounting a total of 50% total CPU usage and leaving 50% of idle time. When assigning to an 1055t X6 (1 worker/6 threads), it uses all cores but amounting 16.66% of total CPU usage.
Any reason for that? Is it planned to be redesigned to use 100% of all cores?

R.D. Silverman · 2010-11-17, 16:03

Quote:

Originally Posted by otutusaus

Whenever I run factoring it's limited to "one core job", even if I assign more.
For example, setting up factoring on a Core2 Duo (1 worker/2 threads), it uses both cores but amounting a total of 50% total CPU usage and leaving 50% of idle time. When assigning to an 1055t X6 (1 worker/6 threads), it uses all cores but amounting 16.66% of total CPU usage.
Any reason for that? Is it planned to be redesigned to use 100% of all cores?

Your question assumes facts that are false.

otutusaus · 2010-11-17, 16:11

Quote:

Originally Posted by R.D. Silverman

Your question assumes facts that are false.

Can you point out what is false?

R.D. Silverman · 2010-11-17, 16:17

Quote:

Originally Posted by otutusaus

Can you point out what is false?

Your assumption that less than 100% of the processing capability is being used.

otutusaus · 2010-11-17, 16:20

Do you mean that there is a bottleneck when factoring that doesn't allow the use of more processing capability? My task manager is telling me that CPU usage in my 1055t X6 is 16.66%.

Mini-Geek · 2010-11-17, 16:31

Quote:

Originally Posted by R.D. Silverman

Your assumption that less than 100% of the processing capability is being used.

Assuming he's using Prime95's TF, this is an accurate assumption. This isn't a case where someone might think that only 50% of the processing capability is being used due to hyperthreading; it's really only using one core out of two or six.

Quote:

Originally Posted by otutusaus

Whenever I run factoring it's limited to "one core job", even if I assign more.
For example, setting up factoring on a Core2 Duo (1 worker/2 threads), it uses both cores but amounting a total of 50% total CPU usage and leaving 50% of idle time. When assigning to an 1055t X6 (1 worker/6 threads), it uses all cores but amounting 16.66% of total CPU usage.
Any reason for that? Is it planned to be redesigned to use 100% of all cores?

First, I'll note that you are correct that the TF of Prime95 is only made to work on a single core, no matter how many threads you assign that worker. I think the reason is simply that both the FFT (LL/P-1) and TF code was originally written to be single-threaded only, and only the FFT code has been updated for multi-threading so far. I don't know of an exact plan to allow it to use more, but I'd imagine it's in the future plans. In the mean time, you can run multiple TF jobs in parallel, or use other software like Factor5 that is multi-thread enabled (but Factor5 is much slower per core than Prime95; usually it's just used for factoring numbers too large for Prime95).

otutusaus · 2010-11-17, 16:55

Quote:

Originally Posted by Mini-Geek

Assuming he's using Prime95's TF, this is an accurate assumption.

Oops, sorry I forgot to mention that. Yes, I am using Prime95.

Quote:

Originally Posted by Mini-Geek

First, I'll note that you are correct that the TF of Prime95 is only made to work on a single core, no matter how many threads you assign that worker.

You got my point.

Quote:

Originally Posted by Mini-Geek

In the mean time, you can run multiple TF jobs in parallel, or use other software like Factor5 that is multi-thread enabled

Thanks for the link. Anyhow, any plans for multithreading Prime95 FT?

petrw1 · 2010-11-17, 17:19

Quote:

Originally Posted by otutusaus

Thanks for the link. Anyhow, any plans for multithreading Prime95 FT?

I'd be curious to ask why? On Dual Core and above PCs like you are talking about all but the largest of TF assignments will finish in under a day; the bulk of server assigned TF will complete in hours.

As pointed out above you can certainly run a seperate TF on each core.

ckdo · 2010-11-17, 19:13

Without having tried it, I assume that if you configure Prime95 to run LL tests across multiple cores, and TF is being done as part of the LL assignment, the TF part runs on one core only with the rest idling away. So much for the "last bit of TF after P-1" idea...

otutusaus · 2010-11-17, 21:58

Quote:

Originally Posted by petrw1

I'd be curious to ask why? On Dual Core and above PCs like you are talking about all but the largest of TF assignments will finish in under a day; the bulk of server assigned TF will complete in hours.

I have some PC's working a few hours a day. I think it would be better to be able to send FT results more often (multicore) than having several FT tests running (single core), specially in the case of 6 cores.

Quote:

Originally Posted by petrw1

As pointed out above you can certainly run a seperate TF on each core.

That's what I have been doing up to now.

Uncwilly · 2010-11-18, 00:17

TF does not gain through-put by trying to do it on multiple cores. You will turn in more results per time period by having one core per test.

2010-11-17, 15:58	#1
otutusaus Nov 2010 Ann Arbor, MI 2·47 Posts	Why factoring is single-core designed? Whenever I run factoring it's limited to "one core job", even if I assign more. For example, setting up factoring on a Core2 Duo (1 worker/2 threads), it uses both cores but amounting a total of 50% total CPU usage and leaving 50% of idle time. When assigning to an 1055t X6 (1 worker/6 threads), it uses all cores but amounting 16.66% of total CPU usage. Any reason for that? Is it planned to be redesigned to use 100% of all cores?

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2010-11-17, 16:20	#5
otutusaus Nov 2010 Ann Arbor, MI 2·47 Posts	Do you mean that there is a bottleneck when factoring that doesn't allow the use of more processing capability? My task manager is telling me that CPU usage in my 1055t X6 is 16.66%.

2010-11-17, 19:13	#9
ckdo Dec 2007 Cleves, Germany 2·5·53 Posts	Without having tried it, I assume that if you configure Prime95 to run LL tests across multiple cores, and TF is being done as part of the LL assignment, the TF part runs on one core only with the rest idling away. So much for the "last bit of TF after P-1" idea...

2010-11-18, 00:17	#11
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 7×37×41 Posts	TF does not gain through-put by trying to do it on multiple cores. You will turn in more results per time period by having one core per test.