Why an operating system crush

Hi,

I want to learn some aspects of a operating system and CPUs? Like...

** Why an operating system hang on by a program crush? I think that there must be always a way of terminating a client program, but it does not.
** What is the signal of that I computer really stuck and nothing to do except to restart?
** What is going on when a CPU is Idle, or why usually the Idle Process is the highest cpu time on task manager process list :)

You see I have some question and more could be comes, give me some clear image of understanding about OS and mostly Microsoft centered explanation?

Thanks.



karanbaAsked:
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programmer1024Commented:
1) On Windows 2000 and later, you can terminate programs and processes in the Task Manager.

2) You can't do anything and anything you have clicked on does not appear.

3) The CPU constantly running when it is "idle." It constantly checks for user actions and program/process instructions in the message queue.

Hope this helps.
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karanbaAuthor Commented:
Please make some more qualified answers, point reference for future reading, give me the clues that no one easily reach :). I am a web programmer, that meeans I know Taks manager terminates but sometimes it does not,  do not be afraid that it will be to technical.  ;)

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b0fhCommented:
If you cannot terminate an application in Task Manager, right-click and select Go To Process.  Then, right-click the process and you can terminate either the specific process or it's entire tree.  

You cannot always terminate processes via Task Manager b/c they may be protected.  In such a case, even an administrator does not always have enough privileges to terminate such a process.  There are ways around this, but they are not advised.  This is generally for a good reason.  (Try terminating all instances of lsass.exe and watch your machine tell you that it will restart in 30 seconds).  


If you hit CTRL-ALT-DEL and get no response, you're probably hosed --  unless of course, the keyboard is just not responding -- check by opening/interacting with an application using the mouse.  There is not necessarily any "Gold Standard" for rebooting a machine -- when you are no longer able to get it to respond, it is time to consider a reboot.


System Idle Process is a counter that exists so that you can easily tell what % of the time the CPU is NOT BUSY (rather than adding all active processes' CPU time together).


If you desire answers w/ more detail, please ask more detailed questions  :-)
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karanbaAuthor Commented:
Thanks b0fh, here questions.  

How cpu time can be calculated? I mean it is an ratio over on a time interval that which process get busy the cpu, count how many cycle and calculate then?

Can we watch what an process what it really do? Like, we know the process id and want to see if it do I/O to hard disk, or use network to get data, or interacting with a local program, when does it start, does have a parent process or has child process,.. and so on.

Is there a way that a process can hide itself  from task manager.

How many individual process can be run on a single cpu?

thanks



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b0fhCommented:
Check out SysInternals (now part of Microsoft) tools, they can help you.      http://www.microsoft.com/technet/sysinternals/default.mspx

I would look at regmon, filemon, and portmon.  They will tell you what files, registry keys, and ports that processes are using.

Yes, a process can hide itself from task manager.  Check out Rootkit Revealer (again from SysInternals) and its related documentation for more information on how this is done.

Calculating CPU time... for a specific process is done for you in Task Manager.  Use Performance Monitor (start, run, perfmon.exe) and add Processor performance counters to trend overall CPU performance in a number of ways.

# of processes per single CPU -- really depends on what each process is doing... it only takes one bad apple to spoil the bunch.

I hope this answers everything.
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