overhead

can someone please explain me what is overhead , payload, header and packet. As far as i know a packet is the whole data that is to be transmitted. This packet consists of the actual data which i think is the payload and the source/destination information of the packet is in the header. So a packet consists of header and payload. So what is this overhead. is overhead a part of the header. I got this from the net "Packet overheard includes all the extra bytes of information that are stored in the packet header" the header already contains source/destination info. What are the extra bytes of

Does using virtual inheritance in C++ have a runtime penalty in compiled code, when we call a regular function member from its base class? Sample code: class A { public: void foo(void) {} }; class B : virtual public A {}; class C : virtual public A {}; class D : public B, public C {}; // ... D bar; bar.foo (); There may be, yes, if you call the member function via a pointer or reference and the compiler can't determine with absolute certainty what type of object that pointer or reference points or refers to. For example, consider: void f(B* p) { p->foo(); } void g() { D bar; f(&bar); }

Are there are any performance cost by creating, throwing and catching exceptions in Java? I am planing to add 'exception driven development' into a larger project. I would like to design my own exceptions and include them into my methods, forcing developers to catch and do appropriate work. For example, if you have a method to get a user from the database based on a name. public User getUser(String name); However, it is possible that the user might be null and it is common to forget to check this before using a User's public method. User user = getUser("adam"); int age = user.getAge(); which

I am a student in Computer Science and I am hearing the word "overhead" a lot when it comes to programs and sorts. What does this mean exactly? corsiKa It's the resources required to set up an operation. It might seem unrelated, but necessary. It's like when you need to go somewhere, you might need a car. But, it would be a lot of overhead to get a car to drive down the street, so you might want to walk. However, the overhead would be worth it if you were going across the country. In computer science, sometimes we use cars to go down the street because we don't have a better way, or it's not

Duplicate: What is the memory consumption of an object in Java? Assuming Java 1.6 JVM on 64-bit Linux on an Intel or AMD box, creating a simple object uses how much memory overhead in bytes? For example, each row in a 2-dimensional array is a separate object. If my array is large, how much RAM will I be using? That will depend on which JVM you use. Assuming that you are not using a JVM with compressed pointers the array will consume: 8 bytes for the type pointer. 4 bytes for the array length. 8 bytes for each element in the array (these are pointers to the actual objects). Sum: 8+4+len*8 bytes

When measuring elapsed time on a low level, I have the choice of using any of these: System.currentTimeMillis(); System.nanoTime(); Both methods are implemented native . Before digging into any C code, does anyone know if there is any substantial overhead calling one or the other? I mean, if I don't really care about the extra precision, which one would be expected to be less CPU time consuming? N.B: I'm using the standard Java 1.6 JDK, but the question may be valid for any JRE... brettw The answer marked correct on this page is actually not correct. That is not a valid way to write a

What is the memory overhead of having an empty vector vs having a pointer to a vector? Option A: std::vector<int> v; Option B: std::vector<int> *v = NULL; I believe that option B takes 1 32 bit pointer (assuming 32 bit here) How much memory does the empty 'v' take up? Éric Malenfant As for the question as asked: It depends on the implementation. With MSVC 7.1 this: std:: cout << sizeof(std::vector<int>) << std::endl; gives me 16 (bytes). (3 pointers: begin, end, and end of capacity, plus an allocator) However it should be noted that the pointer-to-vector gives it a larger overhead: in both