Does Windows 7 task manager Performance tab show all RAM and CPU usage for non-admin users?

Question

I'm trying to specify computer upgrades for our CAD computers. IT refuses to give me admin privileges even though I'm the de facto CAD manager. Most of our computers have 8 GB RAM, but I notice mine rarely goes over 6 GB used if I check the "performance" tab of task manager. I know the "Processes" tab is useless for monitoring my overall system needs as it doesn't show administrator tasks. But what about the "Performance" tab? Is it truly showing me overall usage, or just usage for my user's programs? Overall physical memory usage rarely seems to go much over 6 GB (but definitely not over 7 GB), even when I have a couple CAD files open and my typical 20-50 Chrome tabs. I get slowdowns or lag that seem to be from maxing out either RAM or CPU, but Task Manager does not seem to corroborate this. Is it because it is not accounting for administrator tasks?

Answer 1

It is truly showing overall usage.

You can find the same information, but with far more individual counters, in Performance Monitor (Run perfmon.exe) or Resource Monitor.

Keep in mind that the granularity in Task Manager is quite coarse - it is only updated once per second by default, once every half a second at most. For CPU usage each graphed point is essentially showing the average CPU usage in the preceding interval; spikes in usage can "fall between the cracks".

Also note that these tools do involve code running in at least one thread, so they affect the system being measured; you are not seeing what would be happening if you weren't looking. Usually this difference is insignificant, but it's there.

You appear to have hyperthreading enabled. You should know that that really only gives you four cores' worth of performance in the long term, though it can sometimes give you more than that in terms of responsiveness. The CPU graphs you are seeing of the Windows scheduler's normal behavior, which is to try to use only one logical pprocessor of a core at one time, thus not splitting the core's CPU power between two threads.

The overall CPU usage percentage shown there, "20%", in this case, is sort of misleading when hyperthreading is enabled. Suppose that only one LP out of each core was in use, each 100%. The overall usage would show 50%. Now suppose all logical processors were in use, each 100%. The overall usage would show 100% but you would not be getting twice as much work done as before. 40% more is about the best that can be expected.

Hyperthreading aside... when you are talking about responsiveness, it doesn't matter if there's 50% of your total CPU power available, or even 80%, as a long-term average. (In this business, an average over a one second interval is "long term".) What matters is if it's available right now. So the CPU graphs can be useful for figuring out the long term impact of CPU-intensive jobs, but not so much for understanding responsiveness issues. For that you probably want to look into the Windows Performance Toolkit.