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 [URL="https://www.mersenneforum.org/showthread.php?t=2299"]this[/URL] 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

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.

[QUOTE=Marsupial7;512802]Hello all,


I looked around the forum to find the answer to my question but only found [URL="https://www.mersenneforum.org/showthread.php?t=2299"]this[/URL] 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[/QUOTE]

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.

Hello and thank you for the welcome.




Settings under Test>Worker Windows is, respectively:
[LIST][*]# 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[/LIST]

CPU Information:
[LIST][*]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[/LIST]

Thank you.

[QUOTE=Marsupial7;512807]Hello and thank you for the welcome.




Settings under Test>Worker Windows is, respectively:
[LIST][*]# 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[/LIST]

CPU Information:
[LIST][*]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[/LIST]

Thank you.[/QUOTE]

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.

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

[QUOTE=pinhodecarlos;512837]Your laptop is throttling, that also happens on my laptop when I set client to use all cores/threads.[/QUOTE]

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

[QUOTE=axn;512849]Throttling will still show 100% cpu usage, just that the iterations times will be slower.[/QUOTE]


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.

[QUOTE=pinhodecarlos;512851]ivybridge[/QUOTE]
delid...

[QUOTE=LaurV;513103]delid...[/QUOTE]

Paul underwood.

[QUOTE=pinhodecarlos;513109]Paul underwood.[/QUOTE]

Wha?

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

:ch: