Interesting GPU/CPU Usage

EZ1 · #1 09-11-2011, 04:16 PM

I was just running the London free flight to watch my GPU and CPU usage to see how lots of buildings affect them. I dropped down to around 2000 feet and started following the river from the Tower Bridge Eastward to the sea. While over central London the GPU usage fluctuated between 70% and 80% which I thought was pretty low considering the buildings. I have “Unlimited Building” configured. The CPU usage was distributed fairly evenly over 4 cores running around 50% to 60% on each. The CPU usage stayed consistent for the rest of my flight. However, as I left London and got into the country side the GPU usage maxed out and stayed there until I quit the mission. That is exactly opposite of what I expected. Also, as I posted before, when the GPU maxes out I start seeing usage on the second GPU (not running SLI).

As for I/O I was just watching the HD access light which only blinked once or twice a second throughout the flight. If there was a lot of I/O going on it was happening mostly in the RAID cache.

Anyone have an explanation?

albx · #2 09-11-2011, 04:21 PM

Quote:

Originally Posted by EZ1

I was just running the London free flight to watch my GPU and CPU usage to see how lots of buildings affect them. I dropped down to around 2000 feet and started following the river from the Tower Bridge Eastward to the sea. While over central London the GPU usage fluctuated between 70% and 80% which I thought was pretty low considering the buildings. I have “Unlimited Building” configured. The CPU usage was distributed fairly evenly over 4 cores running around 50% to 60% on each. The CPU usage stayed consistent for the rest of my flight. However, as I left London and got into the country side the GPU usage maxed out and stayed there until I quit the mission. That is exactly opposite of what I expected. Also, as I posted before, when the GPU maxes out I start seeing usage on the second GPU (not running SLI).

As for I/O I was just watching the HD access light which only blinked once or twice a second throughout the flight. If there was a lot of I/O going on it was happening mostly in the RAID cache.

Anyone have an explanation?

alot of bugs?

senseispcc · #3 09-11-2011, 05:15 PM

Try to go under 200 ft. over London and there the fps get a big hit. Especially over the Tower, the Parliament and Buckingham Palace... But in a real fight it never happened.

kestrel79 · #4 09-11-2011, 05:15 PM

Does that 1C splash screen bug still happen where it makes GPU's run really slow clock speed?

I'm running the official version of the game (no beta patch) with an ATi 5850 should I get rid of this screen? Or is this an old issue?

EZ1 · #5 09-11-2011, 05:28 PM

I've done the low flight thing many times, but I wanted to see how the CPU and GPU usage looked over varying landscapes. What I am seeing looks like the GPU is begin under utilized in some cases for some reason. In other situations like in a typical combat mission over the channel, the GPU stays maxed out as I would expect.

NedLynch · #6 09-11-2011, 06:03 PM

I've had the same experience regarding gpu usage, however my gpu usage as measured with afterburner has gone up significantly (from 60-80% to 80-99%) after the beta patch, which I do see as an improvement.

DrSanchez · #7 09-11-2011, 09:19 PM

most probably the cities take a lot of cpu power as well as gpu power. Think about all those LOD swaps and all the data that has to be sent to gpu. gpu is not showing 100% usage because it was waiting for the cpu. therefore in that situation the cpu is the bottle neck.

In the countryside there's not a lot of the cpu to do so the gpu is able to run at full tilt.

EZ1 · #8 09-11-2011, 09:36 PM

But the CPU usage stays relatively low and does not fluctuate regardless of the GPU usage.

DrSanchez · #9 09-11-2011, 09:50 PM

that's more than likely windows spreading the threads across all available cores. try it with a game you know is single threaded and you'll see spread 50/50 (if you're running a dual core) even though it spreads the threads it can never go above 100% total for a single thread.

plus as cod is multi threaded (I think) there could be situations where 1 thread is stalled waiting for another thread to release the data it want's to work on. this can stall the cpu also.

Igo kyu · #10 09-12-2011, 12:18 AM

Quote:

Originally Posted by EZ1

But the CPU usage stays relatively low and does not fluctuate regardless of the GPU usage.

I suspect (I would welcome clarification from someone who really knows) that Hyperthreaded CPUs only ever run up to half speed, because there are half the number of cores that Windows thinks there are, and TANSTAAFL.