linux memory management in portable ubuntu?

[Net]

i put this in programming since it would make more sense to the programmer then the non-programming linux user. If it is better suited for operating system please move.

memory is handled differently in linux vs windows. for instance how memory is allocated in a struct.

if I program under portable ubuntu running in windows will it be the same as linux? all the querks, memory management, etc...

my next class is all under linux. a part of the class they will take our code, put bugs in it and as a test we debug it in their lab which runs linux.

 

[Nothinman]

Ubuntu is Linux. Different versions of gcc may allocate things differently but I doubt you'll be getting deep enough for that to matter.

 

[Net]

Ubuntu is Linux. Different versions of gcc may allocate things differently but I doubt you'll be getting deep enough for that to matter.

i know. i'm concerned that since its running ontop of windows that it might be more like a virtual machine. which might cause problems?

 

[tfinch2]

Originally posted by: net

Ubuntu is Linux. Different versions of gcc may allocate things differently but I doubt you'll be getting deep enough for that to matter.

i know. i'm concerned that since its running ontop of windows that it might be more like a virtual machine. which might cause problems?

It is a virtual machine.

 

[Nothinman]

i know. i'm concerned that since its running ontop of windows that it might be more like a virtual machine. which might cause problems?

It is a virtual machine, nothing knows it's in the VM and minus the emulated hardware and such nothing is different.

 

[postmortemIA]

you can use gcc on windows,

how struct is stored in memory it depends of programmer, whether he decides to put it on heap or stack, for example.

 

[Gamingphreek]

Originally posted by: postmortemIA
you can use gcc on windows,

how struct is stored in memory it depends of programmer, whether he decides to put it on heap or stack, for example.

Exactly - I'm not sure what you mean by memory is handled different.

While the request might be scheduled and processed different but the language and the allocator calls remain the same.

For instance:
Calling the 'new' allocator will request space on the heap. Instantiating statically will request space on the stack. (Of course there is a bit more than those 2 stipulations as to where it goes).

-Kevin

 

[Nothinman]

Exactly - I'm not sure what you mean by memory is handled different.

I figured he meant the actual position in memory which can change with different compiler versions, options, etc.

 

[postmortemIA]

Originally posted by: Nothinman

Exactly - I'm not sure what you mean by memory is handled different.

I figured he meant the actual position in memory which can change with different compiler versions, options, etc.

I doubt any compiler will allocate more memory space than needed for a struct, so even if there are differences, they are irrelevant. The only relevant difference would be stack vs hep vs managed environment (Java, .NET)

 

[Net]

Exactly - I'm not sure what you mean by memory is handled different.

http://i52.photobucket.com/alb...g14/jm45nt/structs.jpg

so now you know you can save on memory by ordering your struct elements, heh.

// 10 bytes wasted in windows
struct a {
char c;
double v;
char c2;
int i;
} *p;

// only 2 bytes wasted in windows
struct a2 {
double v;
char c;
char c2;
int i;
} *p;

 

[Nothinman]

I doubt any compiler will allocate more memory space than needed for a struct, so even if there are differences, they are irrelevant. The only relevant difference would be stack vs hep vs managed environment (Java, .NET)

I mainly meant order, i.e. does the int variable i come before char c in memory or vice versa. And different versions of compilers optimize differently so things can get shuffled around. And as net says with structs there's alignment to think about too.

 

[degibson]

Originally posted by: Nothinman

I doubt any compiler will allocate more memory space than needed for a struct, so even if there are differences, they are irrelevant. The only relevant difference would be stack vs hep vs managed environment (Java, .NET)

I mainly meant order, i.e. does the int variable i come before char c in memory or vice versa. And different versions of compilers optimize differently so things can get shuffled around. And as net says with structs there's alignment to think about too.

It depends on the target machine too. It may be wise to not fully pack a struct (or maybe explicitly pad the struct) for performance reasons.

For the OP:

Originally posted by: net
if I program under portable ubuntu running in windows will it be the same as linux? all the querks, memory management, etc...

If your program is correct, it will run the same. Correct programs, especially 'assignment-level programs' are almost always independent of the virtual address structure. If your code breaks when the memory manager changes, its probably indicative of a bug in your code.