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Old 2019-04-05, 20:02   #1
Marsupial7
 
Apr 2019

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Default 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
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Old 2019-04-05, 20:15   #2
Uncwilly
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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.
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Old 2019-04-05, 20:18   #3
petrw1
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Quote:
Originally Posted by Marsupial7 View Post
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.
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Old 2019-04-05, 20:24   #4
Marsupial7
 
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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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Old 2019-04-05, 22:28   #5
dcheuk
 
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Quote:
Originally Posted by Marsupial7 View Post
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.
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Old 2019-04-06, 06:20   #6
pinhodecarlos
 
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Your laptop is throttling, that also happens on my laptop when I set client to use all cores/threads.
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Old 2019-04-06, 12:08   #7
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Quote:
Originally Posted by pinhodecarlos View Post
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.
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Old 2019-04-06, 12:17   #8
pinhodecarlos
 
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Quote:
Originally Posted by axn View Post
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.
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Old 2019-04-08, 16:14   #9
LaurV
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Quote:
Originally Posted by pinhodecarlos View Post
ivybridge
delid...
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Old 2019-04-08, 16:36   #10
pinhodecarlos
 
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Quote:
Originally Posted by LaurV View Post
delid...
Paul underwood.
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Old 2019-04-08, 19:03   #11
paulunderwood
 
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Quote:
Originally Posted by pinhodecarlos View Post
Paul underwood.
Wha?

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


Last fiddled with by paulunderwood on 2019-04-08 at 19:20
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