Re: Efficient memory allocation

Chris,
If I use 'placement new' to construct an object in the pre-allocated memory
(allocated by VirtualAlloc()) and then delete that object, what happens to
memory space occupied by that object? Is it still valid?

"Chris Becke" <chris.becke@xxxxxxxxx> wrote in message
news:%23b0vX$ZMIHA.5208@xxxxxxxxxxxxxxxxxxxxxxx
1. Call VirtualAlloc once - far easier for you to manage a single object
than 3000.

2. VirtualAlloc will allocat the memory only. to construct your objects
you would need to use 'placement new'.
http://www.google.com/search?q=placement+new for more info on that.

3. VirtualAlloc allocates 4K pages of memory at a time. HeapAlloc
allocates dword aligned memory thats is an arbitrary size - by subdividing
memory it internally allocates using VirtualAlloc.

4. If you are writing a service or application prone to causing heap
fragmentation then you probably should use the low fragmentation heap.

"Kürþat" <xx@xxxxxx> wrote in message
news:eeQUKuZMIHA.5208@xxxxxxxxxxxxxxxxxxxxxxx
Hi,

In my IOCP based server application I want to pre-allocate a certain
amount of memory for later use. Preallocated memory will be used with
overlapped I/O operations and be locked as long as I/O is pending. Using
VirtualAlloc () and page aligned allocation is efficient way to allocate
memory as long as I research.

But I can't figure out some points :

1- Suppose I want to preallocate memory for 3000 OVERLAPPED derived
objects.I will later use those objects with overlapped I/O and IOCP
framework. If page size is 4K, I need 3000 * 4K = 12000K of memory.Should
I allocate whole 12000K making one VirtualAlloc () call or call
VirtualAlloc () 3000 times?

2- Is it right to use VirtualAlloc () and VirtualFree () with objects?
Can they create and destroy objects (are c.tor and d.tor invoked?)

3- What is the difference between HeapAlloc-Free and VirtualAlloc-Free?

4- What is the Low-fragmentation Heap? Should I use this heap in my
server instead of normal memory?

Thanks in advance.





.

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