C / C++ / MFC

How CPU uage is calulcated?

28-Jul-08 1:47

Rajesh R Subramanian wrote:
BTW, I love infinite loops like this:

while(2)//Be twice as confident!
{
//do stuff here
}

I like the infinite-almost-for-sure ones:

while (! ProtonDecayOccurred )
{
  // do ordinary stuff here
}
// OMG!

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: OT (THHB attempt 3)

Mark Salsbery28-Jul-08 7:34

Mark Salsbery

28-Jul-08 7:34

Rajesh R Subramanian wrote:
while(2)//Be twice as confident!

hmmm....I don't agree. 2 in binary is still only 1 set bit.

I'd use 3 so if one of the bits fails there's another to fall back on.

Poke tongue | ;-P

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

vikramlinux28-Jul-08 0:25

28-Jul-08 0:25

Hi all,
How CPU usage is calculated under windows?

- Vikram S

_AnsHUMAN_ 28-Jul-08 0:34

_AnsHUMAN_

28-Jul-08 0:34

GetProcessMemoryInfo,GetSystemTimes and GetPerformanceInfo may be of some help.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

vikramlinux28-Jul-08 0:35

28-Jul-08 0:35

I don't want the CPU usage but I am interested in knowing how it is calculated.

toxcct28-Jul-08 0:37

toxcct

28-Jul-08 0:37

the API access the hardware directly...

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

vikramlinux28-Jul-08 0:41

28-Jul-08 0:41

Again I want to know
is there any formula which they use to calculate CPU usage.
As far I know any process can use either 0% or 100% CPU at specific instance. So as a result I wanted to know
1) Do they use some time frame to calculate CPU usage?
2) What about multi core systems? What is formula for calculating CPU usage for this kind of hardware?

Luc Pattyn28-Jul-08 2:15

Luc Pattyn

28-Jul-08 2:15

Hi,

this will show you how it can be done.

Assume you go to the shopping mall; don't forget to carry your watch.
Note the entry time ("mallStart")

Now for an arbitrary number of iterations:
- choose a shop i
- note entry time ("istart")
- wander around
- note exit time ("istop")

At the end, note the time you leave the mall ("mallStop")

Now the total time was mallStop-mallStart
and the time spent in shop i was istop-istart (or if you went to shop i more than once, it
was sum of each of the istop minus sum of each of the istart)

And the fraction of time alloted to shop i was (istop-istart)/(mallStop-mallStart)
If you add all the fractions, you will end up less than one, the remainder is the time
spent in the mall but outside the shops, let us call it the idle time.

Now imagine you are a CPU, and the shops are the processes that need to run. There you go.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Voting for dummies? No thanks. Dead | X|

CPallini28-Jul-08 2:22

28-Jul-08 2:22

Thank you very much: now I understand why female processes take far more CPU time than male ones.
Big Grin | :-D

Rajesh R Subramanian28-Jul-08 2:30

Rajesh R Subramanian

28-Jul-08 2:30

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.

Microsoft MVP - Visual C++[^]

CPallini28-Jul-08 21:54

28-Jul-08 21:54

Fix occurred here. Remember to feed your troll today.
Wink | ;)

Rajesh R Subramanian31-Jul-08 3:03

Rajesh R Subramanian

31-Jul-08 3:03

Thanks for the fix. Smile | :)

I think the troll's name should be uni-puke. Laugh | :laugh:

Please leave us our small pleasures, they are small, but they are ours! - Mycroft Holmes ^

.·´¯`·->Rajesh<-·´¯`·.
Microsoft MVP - Visual C++[^]

vikramlinux28-Jul-08 2:48

Deleting Items in CTreeCtrl

28-Jul-08 2:48

Thanks for detailed information !

Adeel Mirza27-Jul-08 23:27

Adeel Mirza

27-Jul-08 23:27

I have derived my own custom class from MFC CTreeCtrl and using this arical

http://www.codeguru.com/cpp/control...ticle.php/c723/

I have made multiple tree selection possible. Now the problem comes while deleting multiple items. I am finding it very complex logically.

The problem is while deleting multiple items, [B][I]"if one of the selected items is a child item and its parent is deleted first, then all the children will be deleted too and all the information about the deleted item will be lost."[I][B].

Can someone help me in finding a good solution? Thanks in advance

Maverick

_AnsHUMAN_ 27-Jul-08 23:48

_AnsHUMAN_

27-Jul-08 23:48

you can delete the selected children first. If after deletion you have some nodes that are still existing you don't delete the parent else you can delete it. You can implement a recursive function for this.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: Deleting Items in CTreeCtrl [modified]

kDevloper28-Jul-08 0:11

kDevloper

28-Jul-08 0:11

I don't found any article in the specified link.
Here one thing is not clear :
do you want to delete multiple tree items at one shot?

If this is the case than,
when a parent and a child is selected of the same node or parent of one node and child of the other node? it's a not valid selection for deletion,if multiple selection is selected in a tree control. D'Oh! | :doh:

Adeel Mirza28-Jul-08 0:30

Adeel Mirza

28-Jul-08 0:30

http://www.codeguru.com/cpp/controls/treeview/misc-advanced/article.php

This is the Link. Surprising it didn't open in your case. This artical is only helpful in selecting multiple items in CTreeView control because MFC does'nt provide functionality to select multiple items in a TreeView Control.

Yes the aim is to delete multiple Tree Items in one shot and there are possibilities in which parents and childs of same catagory are selected, and this problem is arising because of this selection only, that if one of the selected items is a child item and its parent is deleted first, then all the children will be deleted too and all the information about the deleted item will be lost.

If you are saying that its not a valid selection then what restriction should I impose while selecting an item? What should be the valid selection criteria for multiple item deletion according to users point of view??

Maverick

modified on Monday, July 28, 2008 6:36 AM

kDevloper28-Jul-08 0:47

kDevloper

28-Jul-08 0:47

Ok,

The simplest thing i can suggest is that on click of delete, iterate through all selections ,if any selected node is not child one than display a message saying all parents should be selected.. or any thing to the user saying it's not a valid selection.

Regards,
KDevloper

how to share a variable value among two applications?

Adeel Mirza28-Jul-08 2:53

Adeel Mirza

28-Jul-08 2:53

Well I am afraid that it was requirement from the client that the multiple selection can be of any sort, so I have to deal with it that way I can't display any message. Frown | :(

Maverick

rupanu27-Jul-08 23:27

rupanu

27-Jul-08 23:27

I'm using VC++ 6.0;
Suppose a variable is declared in a DLL and there are two functions exported from the DLL. 1st function initializes the variable and the other one accesses it. Is it possible to call first function from one application and call second function from another application to access it? I have tried declaring a static/global variable but it loses initialized value when accessed from 2nd application. #pragma doesn't seem to work as well..

Anyone having any clue about the issue please respond.
Thanks and regards.
R.

Re: how to share a variable value among two applications?

_AnsHUMAN_ 27-Jul-08 23:41

_AnsHUMAN_

27-Jul-08 23:41

probably you need shared memory or you can do it using CreateFileMapping or you can use IPC

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: how to share a variable value among two applications?

CPallini27-Jul-08 23:48

Re: how to share a variable value among two applications?

27-Jul-08 23:48

See here.

rupanu28-Jul-08 1:01

rupanu

28-Jul-08 1:01

well, my compiler gave the following warning:

D:\Testing\testpos\caller.cpp [Warning] `allocate' attribute directive ignored

and after initializing in 1st app the value that I get in 2nd app is 0
I also tried

#pragma data_seg("SHARED")
int i; // 'i' will be initialized later with function1
#pragma data_seg()
#pragma comment(linker, "/section:SHARED,RWS")

but that also gives initialized value in the frst app but gives 0 when accessed from 2nd app.

Re: how to share a variable value among two applications?

CPallini28-Jul-08 1:40