Task Manager CPU idle time

Is mad.

I started Task Manager a few hours ago in order to kill something. Then forgot it was running.

The CPU time for the System Idle Process is now 162:47:58, and clocking up time at between 3 and 4 seconds per second.

I assume this is therefore the sum of the 2-core 4-thread usage per second. But even that doesn't make sense, as I switched the machine on after 9am. so at most 8.25 hours x (at most) 8 = 66 hours.

So where does the 162 hours idle time come from? NT Kernel & System is showing 2:23.32.
_{Edit - corrected the Subject.}

Edited by RobertoS (Mon 01-Jun-15 18:38:12)

http://en.wikipedia.org/wiki/System_Idle_Process

Thanks for that, but it basically doesn't explain what I posted. (By the way I've just corrected the "CPE" in the Subject to "CPU".

The CPU percentage use is working as expected, and as that article explains. However I'm talking about the cumulative CPU time for the Idle Process line in Task Manager.

Even at 100% idle x 2 processors x 4 threads you can't get to the number of hours reported.

The CPU slows down.

So?

So more idle time is available.

LOL.
I don't think we can blame Einstein for such a dramatic discrepancy. Plus, don't forget there are a large number of processes clocking up active time as well.

Which reminds me .... I'll post later in t'Park 'bart 'im.

Edited by RobertoS (Mon 01-Jun-15 20:24:56)

I've always noticed on my 2-core CPU that Total CPU Time is about = 2 x Clock time, most of which is the System Idle Process.

Where do you find the Threading count?

Description of the Intel i7-5500U on the Intel website.

But the arithmetic still doesn't work, as I showed in the OP, even allowing for the "Idle threads" usage as per BatBoy's link - which is what my guess did in a crude way.

As far as I can see, even at 8 threads, in 8.25 hours of absolutely nothing but "Idle", which is impossible, it can't get to over 162 hours of CPU.

Certainly looks like time dilation to me. You sure you haven't got the CPU near a black hole?

Ah, my older Pentium D is single threaded. This is my desktop. I'll have a look at my Intel i5 lappy, which has 4 threads also, tomorrow.

So it seems that a single threaded 2-core processor computes exactly. Your threads must be getting frayed & stretching .

If I have time tomorrow I'll do a screenshot soon after booting up, then one a few hours later.

Sorry, I started the lappy, then left it. Of course it went to stand-by and screwed up the timing. I'll try again tomorrow.

Right, finally got round to it, at least to start with .

Have you taken account of Fast Start-up, a Power Option? PC state is carried forward thro' Shutdown to Start-up, so CPU Times are cumulative.

Think it might not be applicable to Restart rather than Shutdown.

Just getting started. Be back later after a few reboots.

EDIT: How do you make Task Mgr remember its columns? I keep having to re-add CPU Time.

Edited by XRaySpeX (Wed 03-Jun-15 10:38:31)

...is it affecting your PC's performance / output?

Thanks XRaySpeX.

I didn't post yesterday because I loaded Task Manager 40 minutes after a cold boot, having done nothing but log in to Windows. It was showing 191+ hours CPU time., and all the other rows on the top screen were in hours as well. So I concluded for some reason it wasn't clearing down.

Which is what you have just explained!!

So instead of trying to find out from scratch what is going on I have a starting point from you.

IIRC I did do a restart for some other reason, or it may have been a hard switch-off, and that reset it. This system does seem to hang at times, but in an odd way. Not always completely - for instance IE11 may stop responding but will close, and on re-opening works - but slowly. Similar other effects. Thunderbird similarly.

Only "disc" is SSD and fast boot appears to be on. Though booting from SSD on a machine I sent back was even quicker - maybe that wasn't saving the state.

Regarding saving the state, that was one of the clues I had found. Closing IE with tabs open before closing down always results in not just the tabs re-opening as per my options setting, but with the previous contents not the current.

Anyway, another busy day ahead, so I shall not be investigating for now. Thanks again for your input.

Hi camiabz. No, the performance is fine (except when it isn't but the two are not related). See XRaySpeX's post and my reply just now to him.

I shall play around with settings another day, and report back .

I can't fathom out when CPU Times are ever zeroised. I've tried Shutdown from button, Shutdown from menu, Restart. Yet CPU Times continues ever upwards.

My total CPU Time is about 56 hours, so even assuming a factor of 8 (2 core x 4 threads) what was I doing differently 7 uptime hours ago? I'm going to have to monitor it more closely. Of course times may just be modulo.

Any ideas?

Edited by XRaySpeX (Wed 03-Jun-15 16:17:58)

Found out how to set CPU Times back to zero; by a Restart but not Shutdown.

On my Intel® Core� i5-4200U (2-core 4-threads) today after a Restart I ran for 6h 12m and total CPU Time clocked up 24h 47m.

CPU Time / Up Time = 24.783 / 6.200 = 3.997 ~= No. of threads.

So the no. of quoted threads must be in total and not per core as you were thinking. I presume it must work by the hardware scheduler having 4 threads to share out between the 2 cores as and when it sees fit.

Just querying the value of the effort required. It's not a CPU problem, and I doubt if the knowledge gained will actually benefit you, I or anyone else anyway.

That's the argument for nobody in any discipline ever doing pure research.

Exactly! & it is gaining useful knowledge about how your systems behave.

Normally I would agree, but having knowledge of why the CPU reports (or misreports) time will not lead anyone to making their CPU preform better. Hence why I asked whether it was affecting his performance.

Who are you? Galileo's Pope?

Far more important than that!