Limit/throttle CPU usage (110% is too much!)

[Freightyard]

How to limit CPU % usage?

After running ntprime64 for a few years, I've only run into a couple conflicts with other software. Photoshop CS4/5 is one; I have to stop the ntprime service to use Photoshop. Maybe this is a low priority background service that Adobe added... who knows...

NOW, I've hit a wall with Win2K8 Server running IIS. I realized recently that IIS was not compressing the web pages it serves (everything was being served uncompressed).

After some investigation, I realized the IIS configuration TURNS OFF compression when CPU utilization is above 90%. Theoretically, this prevents compression from stealing CPU cycles when the machine is very busy.

Even though ntprime/prime95 runs at lowest priority, it still ALWAYS pins the CPU utilization to 100%. Thus, IIS compression never kicks-in.

Looking for suggestions...

Options I know of:

(1) Disable ntprime on one or more cores (dual quad-core Xeon).
(2) Stop using ntprime altogether.

The machine in question is a production web server (mine). It serves a couple dozen web sites and runs SQL as well. I pay colo fees for power whether I use it or not--so why not use it?

FEATURE REQUEST IDEA??? -- Setting to cause prime95 to "give up" some CPU time?

[gjmccrac]

See Throttle in undoc.txt

You would put

Throttle=90

in Prime.txt

This will use only 90% of the CPU.

[Freightyard]

Thanks! However, it appears the "Throttle" option is a giant FAIL for my predicament.

The CPU graph, below, indicates Throttle=100, 85 and 50. As you can see, Throttle does not limit CPU utilization--instead, Throttle performs duty cycling.

The only option it appears I have is to reduce the number of worker processes. Other thoughts?

[Freightyard]

The best solution I could come up with was to eliminate two worker processes. I'm hoping I removed one from each CPU (dual quad-core) to spread the load out, but I'm not certain exactly how the logical cores and physical cores map to each other.

My present CPU utilization (75%) looks like this:

[lavalamp]

If you only need to be below 90%, then you could put one worker process back on and use 7 out of 8 cores, 7/8 * 100 = 87.5%.

Alternatively, could you not change the value for dynamicCompressionDisableCpuUsage from the default 90 to some other value (like 100)? Or perhaps a value of 101 or -1 would prevent it from ever disabling compression. You may also need to tweak dynamicCompressionEnableCpuUsage.

[lorgix]

Originally Posted by Freightyard

Thanks! However, it appears the "Throttle" option is a giant FAIL for my predicament.

The CPU graph, below, indicates Throttle=100, 85 and 50. As you can see, Throttle does not limit CPU utilization--instead, Throttle performs duty cycling.

...

Other thoughts?

I guess it should depend on how IIS determines CPU utilization, and how long the cycles are.

Anyone know about those things?

[Christenson]

It's windows....which is the first problem....

[imwithid]

In an odd way, this thread has helped bring back to life my laptop. I throttled it to 75% so far which has fooled my oven (an HP DV4) to run the fan at full speed (without having to install supplementary fan control software); now it doesn't get as hot and some extra work gets done.

@ Freightyard re:Christenson

I think he's right.

[Xyzzy]

http://www.mersenneforum.org/showthread.php?t=12286

[imwithid]

Originally Posted by Xyzzy

http://www.mersenneforum.org/showthread.php?t=12286

Thanks for clarifying, Xyzzy.

[kladner]

Originally Posted by Freightyard

How to limit CPU % usage?

After running ntprime64 for a few years, I've only run into a couple conflicts with other software. Photoshop CS4/5 is one; I have to stop the ntprime service to use Photoshop. Maybe this is a low priority background service that Adobe added... who knows...

Just to add my 2 cents to this well-aged thread.....

Until yesterday, I had been running with the onboard ATI graphics on an Asus M4A89GTD Pro/USB3 board, PhenomII 1090T, 8GB RAM, etc. I had not encountered the problem mentioned above with PS CS5 in Win7 Pro (edit) 64bit.

Yesterday, I got a Gigabyte GV-N460OC-1GI graphics card, put it in, and disabled the onboard video, uninstalled the driver, etc. Now, with Prime64 running, Photoshop acts really crippled, taking forever to open a file, and even to fully draw the window elements such as borders. This doesn't happen if P64 is stopped. This is with version 26.6.

I have not yet experimented with throttling, though I will. If it resolves the issue I'd rather go that route than shutting P64 off on one core. So far, I have just stopped P64 before starting Photoshop.

I'll post again when I have more to report.

EDIT: I just saw the thread which points out the "PauseWhileRunning=" line for Prime.txt. This seems to be the best solution overall.