CPU usage is only 50%: how to increase?

Marsupial7 · 2019-04-05, 20:02

Hello all,

I looked around the forum to find the answer to my question but only found this posting which is old but also I'm not sure that it applies to my specific issue.

Issue: When I run Prime95, the Windows 10 task manager indicates only about 50% of CPU is being used. However, when I run the torture test almost 100% is used.

Question: Is there any way that I can have Prime95 utilize as much CPU as possible (akin to torture test or at least just more CPU) when running GIMPS work (e.g. LL or LL-D work)?

Thank you

Uncwilly · 2019-04-05, 20:15

Welcome to GIMPS.

What your settings under Test->Worker Windows?
What type of CPU are you running?

Yes, it should use all of your physical CPU.

petrw1 · 2019-04-05, 20:18

Quote:

Originally Posted by Marsupial7

Hello all,

I looked around the forum to find the answer to my question but only found this posting which is old but also I'm not sure that it applies to my specific issue.

Issue: When I run Prime95, the Windows 10 task manager indicates only about 50% of CPU is being used. However, when I run the torture test almost 100% is used.

Question: Is there any way that I can have Prime95 utilize as much CPU as possible (akin to torture test or at least just more CPU) when running GIMPS work (e.g. LL or LL-D work)?

Thank you

If you have a CPU with Hyperthreading (i7 or i9 intel) then 50% is all you want because for Prime95 only Physical Cores actually matter.

With 4 physical cores if all 4 are 100% busy Windows will report usage as 50% because there are 4 virtual cores not being used.

Configuring Prime95 to use the virtual cores too rarely increases thruput; and even then by very little.

I can't speak for why the stress test got you to 100%; it probably used the virtual cores too.

Marsupial7 · 2019-04-05, 20:24

Hello and thank you for the welcome.

Settings under Test>Worker Windows is, respectively:

# of worker windows: 1
Priority: 1
"Whatever makes most sense"
CPU cores to use: 4
Checked: Use HT for TF
Unchecked: Use HT for LL, P-1, ECM

CPU Information:

i7-4800MQ @ 2.70GHz
4 HT cores
CPU features: Prefetch, SSE, SSE2, SSE4, AVX, AVX2, FMA
L1: 32KB; L2: 256KB; L3: 6MB
Edit: Interestingly, Win10 Task Manager shows different L cache values than what is shown inside Prime95---L1: 256KB; L2: 1MB; L3: 6MB

Thank you.

dcheuk · 2019-04-05, 22:28

Quote:

Originally Posted by Marsupial7

Hello and thank you for the welcome.

Settings under Test>Worker Windows is, respectively:

# of worker windows: 1
Priority: 1
"Whatever makes most sense"
CPU cores to use: 4
Checked: Use HT for TF
Unchecked: Use HT for LL, P-1, ECM

CPU Information:

i7-4800MQ @ 2.70GHz
4 HT cores
CPU features: Prefetch, SSE, SSE2, SSE4, AVX, AVX2, FMA
L1: 32KB; L2: 256KB; L3: 6MB
Edit: Interestingly, Win10 Task Manager shows different L cache values than what is shown inside Prime95---L1: 256KB; L2: 1MB; L3: 6MB

Thank you.

It (50%) looks right if you're running LL/DC test w/o hyperthreading. You may want to do a benchmark to see if you would benefit from utilizing hyperthreading to run Lucas Lehmer Prime test.

I think it also depends on other factors i.e. Windows version. I have a mobile i7 processor w/ hyperthreading, when I run LL test when all physical cores (6) w/o using hyperthreading, task manager shows around 60% to 70%.

For cpu cache, although prime95 does not show the correct cache amount I believe it does not affect performance, but don't quote me on that lol. This has been fixed/improved in v29.7b1.

pinhodecarlos · 2019-04-06, 06:20

Your laptop is throttling, that also happens on my laptop when I set client to use all cores/threads.

axn · 2019-04-06, 12:08

Quote:

Originally Posted by pinhodecarlos

Your laptop is throttling, that also happens on my laptop when I set client to use all cores/threads.

Throttling will still show 100% cpu usage, just that the iterations times will be slower.

pinhodecarlos · 2019-04-06, 12:17

Quote:

Originally Posted by axn

Throttling will still show 100% cpu usage, just that the iterations times will be slower.

So something is wrong with the client because I can’t either run it full power when setting to use all cores. I can see the CPU throttle...my cpu is ivybridge on laptop.

LaurV · 2019-04-08, 16:14

Quote:

Originally Posted by pinhodecarlos

ivybridge

delid...

pinhodecarlos · 2019-04-08, 16:36

Quote:

Originally Posted by LaurV

delid...

Paul underwood.

paulunderwood · 2019-04-08, 19:03

Quote:

Originally Posted by pinhodecarlos

Paul underwood.

Wha?

I can't imagine Carlos pulling his laptop apart to take the chip out and then delidding it.

2019-04-05, 20:02	#1
Marsupial7 Apr 2019 3 Posts	CPU usage is only 50%: how to increase? Hello all, I looked around the forum to find the answer to my question but only found this posting which is old but also I'm not sure that it applies to my specific issue. Issue: When I run Prime95, the Windows 10 task manager indicates only about 50% of CPU is being used. However, when I run the torture test almost 100% is used. Question: Is there any way that I can have Prime95 utilize as much CPU as possible (akin to torture test or at least just more CPU) when running GIMPS work (e.g. LL or LL-D work)? Thank you

2019-04-05, 20:24	#4
Marsupial7 Apr 2019 3 Posts	Hello and thank you for the welcome. Settings under Test>Worker Windows is, respectively: # of worker windows: 1 Priority: 1 "Whatever makes most sense" CPU cores to use: 4 Checked: Use HT for TF Unchecked: Use HT for LL, P-1, ECM CPU Information: i7-4800MQ @ 2.70GHz 4 HT cores CPU features: Prefetch, SSE, SSE2, SSE4, AVX, AVX2, FMA L1: 32KB; L2: 256KB; L3: 6MB Edit: Interestingly, Win10 Task Manager shows different L cache values than what is shown inside Prime95---L1: 256KB; L2: 1MB; L3: 6MB Thank you. Last fiddled with by Marsupial7 on 2019-04-05 at 20:29

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2019-04-05, 20:15	#2
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 2638₁₆ Posts	Welcome to GIMPS. What your settings under Test->Worker Windows? What type of CPU are you running? Yes, it should use all of your physical CPU.

2019-04-06, 06:20	#6
pinhodecarlos "Carlos Pinho" Oct 2011 Milton Keynes, UK 3·17·97 Posts	Your laptop is throttling, that also happens on my laptop when I set client to use all cores/threads.