C / C++ / MFC

Re: Forcing an allocated Heap to physical memory & not to be swaped to the page file.

28-Oct-05 3:04

ja1001 wrote:
Is there any way to keep the Heap (a few MB) in the physical memory?

Back when we used to use GlobalAlloc(), we could specify the GMEM_FIXED flag. I only use new/delete these days, and keeping memory from being swapped to disk is not a concern.

"Take only what you need and leave the land as you found it." - Native American Proverb

Cedric Moonen28-Oct-05 3:13

Cedric Moonen

28-Oct-05 3:13

ja1001 wrote:
It is a very time critical application

Do you need to have a real-time behaviour ? If yes, you will run into troubles because windows is not a real-time operating system ! The CPU time allocated to your program will be shared with the other running processes. You cannot garanty precisions under 10 or 20 msec (depending on a lot of factors).

Re: Forcing an allocated Heap to physical memory & not to be swaped to the page file.

Michael Dunn28-Oct-05 3:24

Michael Dunn

28-Oct-05 3:24

How about turning off the paging file on the server?

--Mike--
Visual C++ MVP Cool | :cool:

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Re: Forcing an allocated Heap to physical memory & not to be swaped to the page file.

Blake Miller28-Oct-05 7:32

Blake Miller

28-Oct-05 7:32

VirtualLock

The VirtualLock function locks the specified region of the process's virtual address space into physical memory, ensuring that subsequent access to the region will not incur a page fault.

BOOL VirtualLock(
LPVOID lpAddress,
SIZE_T dwSize
);

Locking pages into memory may degrade the performance of the system by reducing the available RAM and forcing the system to swap out other critical pages to the paging file. Each version of Windows has a limit on the maximum number of pages a process can lock. This limit is intentionally small to avoid severe performance degradation. Applications that need to lock larger numbers of pages must first call the SetProcessWorkingSetSize function to increase their minimum and maximum working set sizes. The maximum number of pages that a process can lock is equal to the number of pages in its minimum working set minus a small overhead.

Pages that a process has locked remain in physical memory until the process unlocks them or terminates.

To unlock a region of locked pages, use the VirtualUnlock function. Locked pages are automatically unlocked when the process terminates.

If memory was allocated with HeapAlloc, you can use VirtualQueryEx to get an appropriate start address.

Re: Forcing an allocated Heap to physical memory & not to be swaped to the page file.

ja100129-Oct-05 4:49

ja1001

29-Oct-05 4:49

This is what I did and the VirtualQueryEX() returend 0 and nothing in the struct.
What am I doing wrong?

void main(int argc, char *argv[])<br />
{<br />
    DWORD  dwMin, dwMax;<br />
    HANDLE hProcess;<br />
    _MEMORY_BASIC_INFORMATION MemInfo; <br />
<br />
    //Creating the heap<br />
    HANDLE hHeap = HeapCreate(NULL, 1024 * 1024 *20, 1024 * 1024 * 30);<br />
	<br />
	hProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, GetCurrentProcessId());<br />
    if (hProcess == INVALID_HANDLE_VALUE)<br />
    {<br />
        printf( "OpenProcess failed (%d)\n", GetLastError() );<br />
        return;<br />
    }<br />
    if (SetProcessWorkingSetSize(GetCurrentProcess(), 1024 * 1024 *20, 1024 * 1024 *30) != 0)<br />
    {<br />
	printf("Process Size Set!\n");<br />
    }<br />
    else<br />
    {<br />
	printf("Error in seting the Process Size!\n");<br />
    }<br />
    printf("%d\n",VirtualQueryEx(hProcess, hHeap, &MemInfo , 1024 * 1024 *20));<br />
    printf("\n MemoryRegionSize: %d\n", MemInfo.RegionSize);<br />
	<br />
    if (VirtualLock(MemInfo.BaseAddress, MemInfo.RegionSize) != 0)<br />
    {<br />
	printf("Virtual Lock Success!!!\n");<br />
    }<br />
    else<br />
    {<br />
	printf("Virtual Lock Failed!!!\n");<br />
    }	<br />
    CloseHandle(hProcess);<br />
}

HELP?!?!

Re: Forcing an allocated Heap to physical memory & not to be swaped to the page file.

Blake Miller31-Oct-05 3:21

Blake Miller

31-Oct-05 3:21

The heap create makes a 'region' of memory available thorugh the API. To determine where the memory is actually located, you must use the pointer returned from HeapAlloc. Allocate a small block of memory, say 8 bytes, using HeapAlloc and then pass that pointer into the VirtualQueryEx function.

LPVOID lpMyMem = HeapAlloc(hHeap, 0, 8);

Also, VirtualQueryEx size is sizeof() not the size of the memory you think you got.

VirtualQueryEx( hProcess, lpMyMem, &MemInfo, sizeof(MemInfo) );

This should let you know how much memory the Heap has comitted and reserved, and its true starting address, so you can call VirtualLock.

How to debug an api call that generates an unknown error

Dan Neely28-Oct-05 2:09

Dan Neely

28-Oct-05 2:09

Reposting here since I didn't get any responce in the c# forum.

My app's written in c#, but the error's being generated by a win32 api call. I'm using the following 3 api calls as demonstrated in the msdn article to monitor changes being made to a folder over samba (FileSystemWatcher won't do this). In my test app the water class works perfectly. When I use my watcher class in my main app everything is fine with one copy running. With two copies though, FindNextChangeNotification returns false and generates errorcode 0x64006e as returned by Marshal.GetLastWin32Error(). Win32Exception.Message describes this as an uknown error, and no error codes with this large a value are listed in msdn, or winError.h. Looking at the code between my main app and my tester I'm not seeing any meaningful differences, and with an unknown error I don't know wehre to be looking. The biggest difference between the two is that when a change occurs my tester just throws up a message box, while my main app reloads all the files in the folder. (There're only a handful so the performance hit from loading everything isn't enough to justify the extra work needed to ID which file was modified).

FindFirstChangeNotification
WaitForMultipleObjects
FindNextChangeNotification
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/obtaining_directory_change_notifications.asp

need help in TrimStart()

sheshidar28-Oct-05 1:58

sheshidar

28-Oct-05 1:58

Hi,
in my project i have to use TrimStart(), for this i included "mscorlib.dll",
but i am getting error message as
D:\Sheshidar\DiplomArbeit\DAP\DAPDlg.cpp(8) : fatal error C1083: Cannot open include file: 'mscorlib.dll': No such file or directory
when i searched for help most of the results giving for VC++.Net, but i am working on VC++6.0
can u help me in this how to overcome on this error and how to add mscorlib.dll for my work.
thanking you
have a nice time
ciao

sheshidar patnam

willy_total28-Oct-05 2:23

willy_total

28-Oct-05 2:23

you can't use the .Net framework in VC 6.0. You will have to use CString or the C-Runtime Library funcitons.

sheshidar28-Oct-05 3:22

sheshidar

28-Oct-05 3:22

Thx Willy, but which C-Runtime Library funcitons i have to use instead of Timstart()?

willy_total31-Oct-05 2:58

willy_total

31-Oct-05 2:58

The easiest way is to use CString LeftTrim, but if you can't use CString. You might be able to use StrTrim, but it will remove the chars from the left and right, so if that will not work for you, you will have to loop through the string.

shivditya28-Oct-05 2:52

shivditya

28-Oct-05 2:52

FRIEND DONT INCLUDE DLL FILE
dll project generates two important files
1).dll
2) .lib
A)copy these both files in your main project debug dirctory
B)copy the header file of the all\required classes used in DLL PROJECT in to main project directory.
Include these header files wherever it does not identify class
if required.
C)IN MAIN PROJECT Goto Menu Project - > settings open the link tab inthat
Object\link modules type the name of lib file with extension
D) In addition copy the dll and lib in your main project folder also remember earlier i asked to copy in debug folder where your exe gets generated now i am asking just for safety.
REMEMBER DLL IS NOT HEADER FILE TO INCLUDE

still problem contact me
shivditya@hotmail.com

|| ART OF LIVING ||

Message Pumps in MFC

Eytukan28-Oct-05 1:02

28-Oct-05 1:02

where can i find examples for Messages Pumps in MFC.. BTW what's a message pump? does it deal with send,post,despatch,etc??

He is like a one-legged man in a bum kicking competition. -Novjot Sidhu

--[v]--

David Crow28-Oct-05 2:54

28-Oct-05 2:54

VivekuniQ wrote:
what's a message pump? does it deal with send,post,despatch,etc??

A program's message loop reads any pending message from the message queue and then dispatches that message back to Windows, which then calls your program's window procedure with that message as a parameter. Without MFC, you are responsible for both the message loop and the window procedure. MFC handles this for you.

"Take only what you need and leave the land as you found it." - Native American Proverb

Eytukan28-Oct-05 4:21

28-Oct-05 4:21

I got this request from my boss.. :

Are you familiar with writing “message pumps”?

This is where you would “push” and “pop” off of dynamic arrays to control threading of commands to API’s.

Multiple threads can “push” messages onto the message stack using a single locking mutex and one single thread “pops” the messages off of the message stack and sends them to the API (using the same locking mutex).

--------------------------------------
what he means actually?.. yeaa we can send messages to the queue.. using sendmessage,postmessage..but should i go for win32 api ? where these messages would be processed by the wndproc ? but whatz the need for mutex here? Confused | :confused:

--[v]--

Eytukan28-Oct-05 4:23

28-Oct-05 4:23

VivekuniQ wrote:
one single thread “pops” the messages off of the message stack and sends them to the API (using the same locking mutex)

whatz this i dont understand.. sends them to the API?? Confused | :confused:

He is like a one-legged man in a bum kicking competition. -Novjot Sidhu

--[v]--

David Crow28-Oct-05 4:48

28-Oct-05 4:48

I'm curious why you are being asked to do something that Windows already does and does well. If you use SendMessage(), control does not return until after the window procedure has processed the message. If you use PostMessage(), control returns immediately.

"Take only what you need and leave the land as you found it." - Native American Proverb

Eytukan28-Oct-05 5:51

28-Oct-05 5:51

i guess he's talking in context with the user defined messages.. i'll get back to you after getting a clear requirement.
thanks.

--[v]--

David Crow28-Oct-05 6:16